Systems and methods for platform rate limiting

ABSTRACT

The present disclosure presents systems and methods for controlling network traffic traversing an intermediary device based on a license or a permit granted for the intermediary device. The systems and methods control a rate of a traffic of a device in accordance with a rate limit identified by a rate limiting license. A rate limiting manager of an intermediary device that processes network traffic between a plurality of clients and a plurality of servers, may identify presence of a rate limiting license that further identifies a performance level. The rate limiting manager may establish a rate limit based on the performance level of the rate limiting license. A throttler of the intermediary may control a rate of receiving network packets in accordance with the rate limit.

RELATED APPLICATIONS

This present application claims priority to a U.S. ProvisionalApplication No. 61/219,264, entitled “Systems and Methods for PlatformRate Limiting”, filed on Jun. 22, 2009, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present application generally relates to data communicationnetworks. In particular, the present application relates to systems andmethods for controlling a rate of a traffic according to a license.

BACKGROUND OF THE INVENTION

An enterprise may provide a service to users accessing servers fromclient machines via intermediaries deployed by the enterprise betweenthe clients and servers. The intermediaries may manage and control thenetwork traffic to enhance the user experience. The enterprise may, fora variety of reasons, determine to control the flow of the networktraffic that traverses the intermediaries. The enterprise may furtherdetermine to control the flow of the network traffic receiving theintermediaries.

BRIEF SUMMARY OF THE INVENTION

The present application is directed towards systems and methods forcontrolling network traffic traversing an intermediary device based on alicense or a permit granted for the intermediary device. The presentapplication is also directed towards systems and methods for controllinga rate of a traffic being received by an intermediary device inaccordance with a rate limit identified by a license or permit. Bycontrolling the rate of the traffic being received by the intermediary,the rate at which the traffic is processed and the resources of theintermediary are utilized may also be controlled.

In some aspects, the present application is directed to a method forcontrolling a rate of a traffic of a device in accordance with a ratelimit identified by a rate limiting license. A rate limiting manager ofan intermediary device that processes network traffic between aplurality of clients and a plurality of servers, may identify presenceof a rate limiting license identifying a performance level. The ratelimiting manager may establish a rate limit based on the performancelevel of the rate limiting license. A throttler of the intermediary maycontrol a rate of receiving network packets in accordance with the ratelimit.

The rate limiting manager may identify the rate limiting license is notpresent and establish a set of one or more rate limit parameters for therate limit for a lower performance level. The lower performance levelmay include the throttler controlling the rate of receiving networkpackets at a slower rate than a rate for identified rate limitinglicenses. In some embodiments, the rate limiting manager identifies atype of hardware platform of the intermediary device. The rate limitingmanager establishes the rate limit based on the type of hardwareplatform and the performance level. In some embodiments, the ratelimiting manager establishes a maximum size of a token bucket inmilliseconds based on the rate limit for the performance level of therate limiting license. The token bucket may determine the maximum totalnumber of tokens used by the throttler to identify the number of datapackets to propagate or throttle in a burst and not in accordance withthe rate limit. In some embodiments, the throttler receives a networkpacket, determines that the token bucket has reached the maximum sizeand discards the network packet in response to the determination. Inother embodiments, the throttler receives a network packet, determinesthat the token bucket has reached the maximum size and waits until anext available token to propagate or throttle a next data packet.

In some embodiments, the rate limiting manager establishes a throughputrate limit in bits per second based on the rate limit for theperformance level of the rate limiting license. In further embodiments,a token generator generates a token for a token bucket at a ratespecified by the throughput rate limit. In yet further embodiments, therate limiting manager establishes a packet rate in packets per secondbased on the rate limit for the performance level of the rate limitinglicense. In some embodiments, the throttler receives a network packethaving a number of bytes, and removes, or sends an instruction toremove, a number of tokens from a token bucket equal to the number ofbytes. In some embodiments, the throttler receives a network packethaving a number of bytes, determines that a number of tokens in a tokenbucket is less than the number of bytes and does not remove a token fromthe token bucket. In some embodiments, the throttler provides thenetwork packet to an excess packet handler.

In other aspects, the present application is directed to a system forcontrolling a rate of a traffic of a device in accordance with a ratelimit identified by a rate limiting license. The system may include arate limiting manager of an intermediary device that processes networktraffic between a plurality of clients and a plurality of serversidentifying presence of a rate limiting license identifying aperformance level. The rate limiting manager may establish a rate limitbased on the performance level of the rate limiting license. A throttlerof the intermediary may controlling a rate of receiving network packetsin accordance with the rate limit.

The details of various embodiments of the invention are set forth in theaccompanying drawings and the description below.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent and better understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a block diagram of an embodiment of a network environment fora client to access a server via an appliance;

FIG. 1B is a block diagram of an embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIG. 1C is a block diagram of another embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIG. 1D is a block diagram of another embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIGS. 1E-1H are block diagrams of embodiments of a computing device;

FIG. 2A is a block diagram of an embodiment of an appliance forprocessing communications between a client and a server;

FIG. 2B is a block diagram of another embodiment of an appliance foroptimizing, accelerating, load-balancing and routing communicationsbetween a client and a server;

FIG. 3 is a block diagram of an embodiment of a client for communicatingwith a server via the appliance;

FIG. 4A is a block diagram of an embodiment of a virtualizationenvironment;

FIG. 4B is a block diagram of another embodiment of a virtualizationenvironment;

FIG. 4C is a block diagram of an embodiment of a virtualized appliance;

FIG. 5A are block diagrams of embodiments of approaches to implementingparallelism in a multi-core system;

FIG. 5B is a block diagram of an embodiment of a system utilizing amulti-core system;

FIG. 5C is a block diagram of another embodiment of an aspect of amulti-core system;

FIG. 6A are block diagrams of an embodiments of a system for controllinga rate of traffic traversing an intermediary device; and

FIG. 6B is a flow diagram of an embodiment of steps of a method forcontrolling a rate of traffic traversing an intermediary device.

In the drawings, like reference numbers generally indicate identical,functionally similar, and/or structurally similar elements.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of reading the description of the various embodimentsbelow, the following descriptions of the sections of the specificationand their respective contents may be helpful:

-   -   Section A describes a network environment and computing        environment which may be useful for practicing embodiments        described herein;    -   Section B describes embodiments of systems and methods for        delivering a computing environment to a remote user;    -   Section C describes embodiments of systems and methods for        accelerating communications between a client and a server;    -   Section D describes embodiments of systems and methods for        virtualizing an application delivery controller;    -   Section E describes embodiments of systems and methods for        providing a multi-core architecture and environment;    -   Section F describes embodiments of systems and methods for        controlling a rate of traffic traversing an intermediary device

A. Network and Computing Environment

Prior to discussing the specifics of embodiments of the systems andmethods of an appliance and/or client, it may be helpful to discuss thenetwork and computing environments in which such embodiments may bedeployed. Referring now to FIG. 1A, an embodiment of a networkenvironment is depicted. In brief overview, the network environmentcomprises one or more clients 102 a-102 n (also generally referred to aslocal machine(s) 102, or client(s) 102) in communication with one ormore servers 106 a-106 n (also generally referred to as server(s) 106,or remote machine(s) 106) via one or more networks 104, 104′ (generallyreferred to as network 104). In some embodiments, a client 102communicates with a server 106 via an appliance 200.

Although FIG. 1A shows a network 104 and a network 104′ between theclients 102 and the servers 106, the clients 102 and the servers 106 maybe on the same network 104. The networks 104 and 104′ can be the sametype of network or different types of networks. The network 104 and/orthe network 104′ can be a local-area network (LAN), such as a companyIntranet, a metropolitan area network (MAN), or a wide area network(WAN), such as the Internet or the World Wide Web. In one embodiment,network 104′ may be a private network and network 104 may be a publicnetwork. In some embodiments, network 104 may be a private network andnetwork 104′ a public network. In another embodiment, networks 104 and104′ may both be private networks. In some embodiments, clients 102 maybe located at a branch office of a corporate enterprise communicatingvia a WAN connection over the network 104 to the servers 106 located ata corporate data center.

The network 104 and/or 104′ be any type and/or form of network and mayinclude any of the following: a point to point network, a broadcastnetwork, a wide area network, a local area network, a telecommunicationsnetwork, a data communication network, a computer network, an ATM(Asynchronous Transfer Mode) network, a SONET (Synchronous OpticalNetwork) network, a SDH (Synchronous Digital Hierarchy) network, awireless network and a wireline network. In some embodiments, thenetwork 104 may comprise a wireless link, such as an infrared channel orsatellite band. The topology of the network 104 and/or 104′ may be abus, star, or ring network topology. The network 104 and/or 104′ andnetwork topology may be of any such network or network topology as knownto those ordinarily skilled in the art capable of supporting theoperations described herein.

As shown in FIG. 1A, the appliance 200, which also may be referred to asan interface unit 200 or gateway 200, is shown between the networks 104and 104′. In some embodiments, the appliance 200 may be located onnetwork 104. For example, a branch office of a corporate enterprise maydeploy an appliance 200 at the branch office. In other embodiments, theappliance 200 may be located on network 104′. For example, an appliance200 may be located at a corporate data center. In yet anotherembodiment, a plurality of appliances 200 may be deployed on network104. In some embodiments, a plurality of appliances 200 may be deployedon network 104′. In one embodiment, a first appliance 200 communicateswith a second appliance 200′. In other embodiments, the appliance 200could be a part of any client 102 or server 106 on the same or differentnetwork 104,104′ as the client 102. One or more appliances 200 may belocated at any point in the network or network communications pathbetween a client 102 and a server 106.

In some embodiments, the appliance 200 comprises any of the networkdevices manufactured by Citrix Systems, Inc. of Ft. Lauderdale Fla.,referred to as Citrix NetScaler devices. In other embodiments, theappliance 200 includes any of the product embodiments referred to asWebAccelerator and BigIP manufactured by F5 Networks, Inc. of Seattle,Wash. In another embodiment, the appliance 205 includes any of the DXacceleration device platforms and/or the SSL VPN series of devices, suchas SA 700, SA 2000, SA 4000, and SA 6000 devices manufactured by JuniperNetworks, Inc. of Sunnyvale, Calif. In yet another embodiment, theappliance 200 includes any application acceleration and/or securityrelated appliances and/or software manufactured by Cisco Systems, Inc.of San Jose, Calif., such as the Cisco ACE Application Control EngineModule service software and network modules, and Cisco AVS SeriesApplication Velocity System.

In one embodiment, the system may include multiple, logically-groupedservers 106. In these embodiments, the logical group of servers may bereferred to as a server farm 38. In some of these embodiments, theserves 106 may be geographically dispersed. In some cases, a farm 38 maybe administered as a single entity. In other embodiments, the serverfarm 38 comprises a plurality of server farms 38. In one embodiment, theserver farm executes one or more applications on behalf of one or moreclients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more ofthe servers 106 can operate according to one type of operating systemplatform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond,Wash.), while one or more of the other servers 106 can operate onaccording to another type of operating system platform (e.g., Unix orLinux). The servers 106 of each farm 38 do not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or medium-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

Servers 106 may be referred to as a file server, application server, webserver, proxy server, or gateway server. In some embodiments, a server106 may have the capacity to function as either an application server oras a master application server. In one embodiment, a server 106 mayinclude an Active Directory. The clients 102 may also be referred to asclient nodes or endpoints. In some embodiments, a client 102 has thecapacity to function as both a client node seeking access toapplications on a server and as an application server providing accessto hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In oneembodiment, the client 102 communicates directly with one of the servers106 in a farm 38. In another embodiment, the client 102 executes aprogram neighborhood application to communicate with a server 106 in afarm 38. In still another embodiment, the server 106 provides thefunctionality of a master node. In some embodiments, the client 102communicates with the server 106 in the farm 38 through a network 104.Over the network 104, the client 102 can, for example, request executionof various applications hosted by the servers 106 a-106 n in the farm 38and receive output of the results of the application execution fordisplay. In some embodiments, only the master node provides thefunctionality required to identify and provide address informationassociated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a webserver. In another embodiment, the server 106 a receives requests fromthe client 102, forwards the requests to a second server 106 b andresponds to the request by the client 102 with a response to the requestfrom the server 106 b. In still another embodiment, the server 106acquires an enumeration of applications available to the client 102 andaddress information associated with a server 106 hosting an applicationidentified by the enumeration of applications. In yet anotherembodiment, the server 106 presents the response to the request to theclient 102 using a web interface. In one embodiment, the client 102communicates directly with the server 106 to access the identifiedapplication. In another embodiment, the client 102 receives applicationoutput data, such as display data, generated by an execution of theidentified application on the server 106.

Referring now to FIG. 1B, an embodiment of a network environmentdeploying multiple appliances 200 is depicted. A first appliance 200 maybe deployed on a first network 104 and a second appliance 200′ on asecond network 104′. For example a corporate enterprise may deploy afirst appliance 200 at a branch office and a second appliance 200′ at adata center. In another embodiment, the first appliance 200 and secondappliance 200′ are deployed on the same network 104 or network 104. Forexample, a first appliance 200 may be deployed for a first server farm38, and a second appliance 200 may be deployed for a second server farm38′. In another example, a first appliance 200 may be deployed at afirst branch office while the second appliance 200′ is deployed at asecond branch office′. In some embodiments, the first appliance 200 andsecond appliance 200′ work in cooperation or in conjunction with eachother to accelerate network traffic or the delivery of application anddata between a client and a server

Referring now to FIG. 1C, another embodiment of a network environmentdeploying the appliance 200 with one or more other types of appliances,such as between one or more WAN optimization appliance 205, 205′ isdepicted. For example a first WAN optimization appliance 205 is shownbetween networks 104 and 104′ and a second WAN optimization appliance205′ may be deployed between the appliance 200 and one or more servers106. By way of example, a corporate enterprise may deploy a first WANoptimization appliance 205 at a branch office and a second WANoptimization appliance 205′ at a data center. In some embodiments, theappliance 205 may be located on network 104′. In other embodiments, theappliance 205′ may be located on network 104. In some embodiments, theappliance 205′ may be located on network 104′ or network 104″. In oneembodiment, the appliance 205 and 205′ are on the same network. Inanother embodiment, the appliance 205 and 205′ are on differentnetworks. In another example, a first WAN optimization appliance 205 maybe deployed for a first server farm 38 and a second WAN optimizationappliance 205′ for a second server farm 38′

In one embodiment, the appliance 205 is a device for accelerating,optimizing or otherwise improving the performance, operation, or qualityof service of any type and form of network traffic, such as traffic toand/or from a WAN connection. In some embodiments, the appliance 205 isa performance enhancing proxy. In other embodiments, the appliance 205is any type and form of WAN optimization or acceleration device,sometimes also referred to as a WAN optimization controller. In oneembodiment, the appliance 205 is any of the product embodiments referredto as WANScaler manufactured by Citrix Systems, Inc. of Ft. Lauderdale,Fla. In other embodiments, the appliance 205 includes any of the productembodiments referred to as BIG-IP link controller and WANj etmanufactured by F5 Networks, Inc. of Seattle, Wash. In anotherembodiment, the appliance 205 includes any of the WX and WXC WANacceleration device platforms manufactured by Juniper Networks, Inc. ofSunnyvale, Calif. In some embodiments, the appliance 205 includes any ofthe steelhead line of WAN optimization appliances manufactured byRiverbed Technology of San Francisco, Calif. In other embodiments, theappliance 205 includes any of the WAN related devices manufactured byExpand Networks Inc. of Roseland, New Jersey. In one embodiment, theappliance 205 includes any of the WAN related appliances manufactured byPacketeer Inc. of Cupertino, Calif., such as the PacketShaper, iShared,and SkyX product embodiments provided by Packeteer. In yet anotherembodiment, the appliance 205 includes any WAN related appliances and/orsoftware manufactured by Cisco Systems, Inc. of San Jose, Calif., suchas the Cisco Wide Area Network Application Services software and networkmodules, and Wide Area Network engine appliances.

In one embodiment, the appliance 205 provides application and dataacceleration services for branch-office or remote offices. In oneembodiment, the appliance 205 includes optimization of Wide Area FileServices (WAFS). In another embodiment, the appliance 205 acceleratesthe delivery of files, such as via the Common Internet File System(CIFS) protocol. In other embodiments, the appliance 205 providescaching in memory and/or storage to accelerate delivery of applicationsand data. In one embodiment, the appliance 205 provides compression ofnetwork traffic at any level of the network stack or at any protocol ornetwork layer. In another embodiment, the appliance 205 providestransport layer protocol optimizations, flow control, performanceenhancements or modifications and/or management to accelerate deliveryof applications and data over a WAN connection. For example, in oneembodiment, the appliance 205 provides Transport Control Protocol (TCP)optimizations. In other embodiments, the appliance 205 providesoptimizations, flow control, performance enhancements or modificationsand/or management for any session or application layer protocol.

In another embodiment, the appliance 205 encoded any type and form ofdata or information into custom or standard TCP and/or IP header fieldsor option fields of network packet to announce presence, functionalityor capability to another appliance 205′. In another embodiment, anappliance 205′ may communicate with another appliance 205′ using dataencoded in both TCP and/or IP header fields or options. For example, theappliance may use TCP option(s) or IP header fields or options tocommunicate one or more parameters to be used by the appliances 205,205′ in performing functionality, such as WAN acceleration, or forworking in conjunction with each other.

In some embodiments, the appliance 200 preserves any of the informationencoded in TCP and/or IP header and/or option fields communicatedbetween appliances 205 and 205′. For example, the appliance 200 mayterminate a transport layer connection traversing the appliance 200,such as a transport layer connection from between a client and a servertraversing appliances 205 and 205′. In one embodiment, the appliance 200identifies and preserves any encoded information in a transport layerpacket transmitted by a first appliance 205 via a first transport layerconnection and communicates a transport layer packet with the encodedinformation to a second appliance 205′ via a second transport layerconnection.

Referring now to FIG. 1D, a network environment for delivering and/oroperating a computing environment on a client 102 is depicted. In someembodiments, a server 106 includes an application delivery system 190for delivering a computing environment or an application and/or datafile to one or more clients 102. In brief overview, a client 10 is incommunication with a server 106 via network 104, 104′ and appliance 200.For example, the client 102 may reside in a remote office of a company,e.g., a branch office, and the server 106 may reside at a corporate datacenter. The client 102 comprises a client agent 120, and a computingenvironment 15. The computing environment 15 may execute or operate anapplication that accesses, processes or uses a data file. The computingenvironment 15, application and/or data file may be delivered via theappliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of acomputing environment 15, or any portion thereof, to a client 102. Inone embodiment, the appliance 200 accelerates the delivery of thecomputing environment 15 by the application delivery system 190. Forexample, the embodiments described herein may be used to acceleratedelivery of a streaming application and data file processable by theapplication from a central corporate data center to a remote userlocation, such as a branch office of the company. In another embodiment,the appliance 200 accelerates transport layer traffic between a client102 and a server 106. The appliance 200 may provide accelerationtechniques for accelerating any transport layer payload from a server106 to a client 102, such as: 1) transport layer connection pooling, 2)transport layer connection multiplexing, 3) transport control protocolbuffering, 4) compression and 5) caching. In some embodiments, theappliance 200 provides load balancing of servers 106 in responding torequests from clients 102. In other embodiments, the appliance 200 actsas a proxy or access server to provide access to the one or more servers106. In another embodiment, the appliance 200 provides a secure virtualprivate network connection from a first network 104 of the client 102 tothe second network 104′ of the server 106, such as an SSL VPNconnection. It yet other embodiments, the appliance 200 providesapplication firewall security, control and management of the connectionand communications between a client 102 and a server 106.

In some embodiments, the application delivery management system 190provides application delivery techniques to deliver a computingenvironment to a desktop of a user, remote or otherwise, based on aplurality of execution methods and based on any authentication andauthorization policies applied via a policy engine 195. With thesetechniques, a remote user may obtain a computing environment and accessto server stored applications and data files from any network connecteddevice 100. In one embodiment, the application delivery system 190 mayreside or execute on a server 106. In another embodiment, theapplication delivery system 190 may reside or execute on a plurality ofservers 106 a-106 n. In some embodiments, the application deliverysystem 190 may execute in a server farm 38. In one embodiment, theserver 106 executing the application delivery system 190 may also storeor provide the application and data file. In another embodiment, a firstset of one or more servers 106 may execute the application deliverysystem 190, and a different server 106 n may store or provide theapplication and data file. In some embodiments, each of the applicationdelivery system 190, the application, and data file may reside or belocated on different servers. In yet another embodiment, any portion ofthe application delivery system 190 may reside, execute or be stored onor distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 15 for executing anapplication that uses or processes a data file. The client 102 vianetworks 104, 104′ and appliance 200 may request an application and datafile from the server 106. In one embodiment, the appliance 200 mayforward a request from the client 102 to the server 106. For example,the client 102 may not have the application and data file stored oraccessible locally. In response to the request, the application deliverysystem 190 and/or server 106 may deliver the application and data fileto the client 102. For example, in one embodiment, the server 106 maytransmit the application as an application stream to operate incomputing environment 15 on client 102.

In some embodiments, the application delivery system 190 comprises anyportion of the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™ and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application delivery system 190 may deliver one ormore applications to clients 102 or users via a remote-display protocolor otherwise via remote-based or server-based computing. In anotherembodiment, the application delivery system 190 may deliver one or moreapplications to clients or users via steaming of the application.

In one embodiment, the application delivery system 190 includes a policyengine 195 for controlling and managing the access to, selection ofapplication execution methods and the delivery of applications. In someembodiments, the policy engine 195 determines the one or moreapplications a user or client 102 may access. In another embodiment, thepolicy engine 195 determines how the application should be delivered tothe user or client 102, e.g., the method of execution. In someembodiments, the application delivery system 190 provides a plurality ofdelivery techniques from which to select a method of applicationexecution, such as a server-based computing, streaming or delivering theapplication locally to the client 120 for local execution.

In one embodiment, a client 102 requests execution of an applicationprogram and the application delivery system 190 comprising a server 106selects a method of executing the application program. In someembodiments, the server 106 receives credentials from the client 102. Inanother embodiment, the server 106 receives a request for an enumerationof available applications from the client 102. In one embodiment, inresponse to the request or receipt of credentials, the applicationdelivery system 190 enumerates a plurality of application programsavailable to the client 102. The application delivery system 190receives a request to execute an enumerated application. The applicationdelivery system 190 selects one of a predetermined number of methods forexecuting the enumerated application, for example, responsive to apolicy of a policy engine. The application delivery system 190 mayselect a method of execution of the application enabling the client 102to receive application-output data generated by execution of theapplication program on a server 106. The application delivery system 190may select a method of execution of the application enabling the localmachine 10 to execute the application program locally after retrieving aplurality of application files comprising the application. In yetanother embodiment, the application delivery system 190 may select amethod of execution of the application to stream the application via thenetwork 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application,which can be any type and/or form of software, program, or executableinstructions such as any type and/or form of web browser, web-basedclient, client-server application, a thin-client computing client, anActiveX control, or a Java applet, or any other type and/or form ofexecutable instructions capable of executing on client 102. In someembodiments, the application may be a server-based or a remote-basedapplication executed on behalf of the client 102 on a server 106. In oneembodiments the server 106 may display output to the client 102 usingany thin-client or remote-display protocol, such as the IndependentComputing Architecture (ICA) protocol manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP)manufactured by the Microsoft Corporation of Redmond, Wash. Theapplication can use any type of protocol and it can be, for example, anHTTP client, an FTP client, an Oscar client, or a Telnet client. Inother embodiments, the application comprises any type of softwarerelated to VoIP communications, such as a soft IP telephone. In furtherembodiments, the application comprises any application related toreal-time data communications, such as applications for streaming videoand/or audio.

In some embodiments, the server 106 or a server farm 38 may be runningone or more applications, such as an application providing a thin-clientcomputing or remote display presentation application. In one embodiment,the server 106 or server farm 38 executes as an application, any portionof the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™, and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application is an ICA client, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla. In other embodiments, theapplication includes a Remote Desktop (RDP) client, developed byMicrosoft Corporation of Redmond, Wash. Also, the server 106 may run anapplication, which for example, may be an application server providingemail services such as Microsoft Exchange manufactured by the MicrosoftCorporation of Redmond, Wash., a web or Internet server, or a desktopsharing server, or a collaboration server. In some embodiments, any ofthe applications may comprise any type of hosted service or products,such as GoToMeeting™ provided by Citrix Online Division, Inc. of SantaBarbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif.,or Microsoft Office Live Meeting provided by Microsoft Corporation ofRedmond, Wash.

Still referring to FIG. 1D, an embodiment of the network environment mayinclude a monitoring server 106A. The monitoring server 106A may includeany type and form performance monitoring service 198. The performancemonitoring service 198 may include monitoring, measurement and/ormanagement software and/or hardware, including data collection,aggregation, analysis, management and reporting. In one embodiment, theperformance monitoring service 198 includes one or more monitoringagents 197. The monitoring agent 197 includes any software, hardware orcombination thereof for performing monitoring, measurement and datacollection activities on a device, such as a client 102, server 106 oran appliance 200, 205. In some embodiments, the monitoring agent 197includes any type and form of script, such as Visual Basic script, orJavascript. In one embodiment, the monitoring agent 197 executestransparently to any application and/or user of the device. In someembodiments, the monitoring agent 197 is installed and operatedunobtrusively to the application or client. In yet another embodiment,the monitoring agent 197 is installed and operated without anyinstrumentation for the application or device.

In some embodiments, the monitoring agent 197 monitors, measures andcollects data on a predetermined frequency. In other embodiments, themonitoring agent 197 monitors, measures and collects data based upondetection of any type and form of event. For example, the monitoringagent 197 may collect data upon detection of a request for a web page orreceipt of an HTTP response. In another example, the monitoring agent197 may collect data upon detection of any user input events, such as amouse click. The monitoring agent 197 may report or provide anymonitored, measured or collected data to the monitoring service 198. Inone embodiment, the monitoring agent 197 transmits information to themonitoring service 198 according to a schedule or a predeterminedfrequency. In another embodiment, the monitoring agent 197 transmitsinformation to the monitoring service 198 upon detection of an event.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of any networkresource or network infrastructure element, such as a client, server,server farm, appliance 200, appliance 205, or network connection. In oneembodiment, the monitoring service 198 and/or monitoring agent 197performs monitoring and performance measurement of any transport layerconnection, such as a TCP or UDP connection. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresnetwork latency. In yet one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures bandwidth utilization.

In other embodiments, the monitoring service 198 and/or monitoring agent197 monitors and measures end-user response times. In some embodiments,the monitoring service 198 performs monitoring and performancemeasurement of an application. In another embodiment, the monitoringservice 198 and/or monitoring agent 197 performs monitoring andperformance measurement of any session or connection to the application.In one embodiment, the monitoring service 198 and/or monitoring agent197 monitors and measures performance of a browser. In anotherembodiment, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of HTTP based transactions. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of a Voice over IP (VoIP) applicationor session. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of a remotedisplay protocol application, such as an ICA client or RDP client. Inyet another embodiment, the monitoring service 198 and/or monitoringagent 197 monitors and measures performance of any type and form ofstreaming media. In still a further embodiment, the monitoring service198 and/or monitoring agent 197 monitors and measures performance of ahosted application or a Software-As-A-Service (SaaS) delivery model.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of one or moretransactions, requests or responses related to application. In otherembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures any portion of an application layer stack, such asany .NET or J2EE calls. In one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures database or SQLtransactions. In yet another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures any method, functionor application programming interface (API) call.

In one embodiment, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of a delivery ofapplication and/or data from a server to a client via one or moreappliances, such as appliance 200 and/or appliance 205. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of delivery of a virtualizedapplication. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of delivery of astreaming application. In another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures performance ofdelivery of a desktop application to a client and/or the execution ofthe desktop application on the client. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresperformance of a client/server application.

In one embodiment, the monitoring service 198 and/or monitoring agent197 is designed and constructed to provide application performancemanagement for the application delivery system 190. For example, themonitoring service 198 and/or monitoring agent 197 may monitor, measureand manage the performance of the delivery of applications via theCitrix Presentation Server. In this example, the monitoring service 198and/or monitoring agent 197 monitors individual ICA sessions. Themonitoring service 198 and/or monitoring agent 197 may measure the totaland per session system resource usage, as well as application andnetworking performance. The monitoring service 198 and/or monitoringagent 197 may identify the active servers for a given user and/or usersession. In some embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors back-end connections between theapplication delivery system 190 and an application and/or databaseserver. The monitoring service 198 and/or monitoring agent 197 maymeasure network latency, delay and volume per user-session or ICAsession.

In some embodiments, the monitoring service 198 and/or monitoring agent197 measures and monitors memory usage for the application deliverysystem 190, such as total memory usage, per user session and/or perprocess. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors CPU usage the applicationdelivery system 190, such as total CPU usage, per user session and/orper process. In another embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors the time required to log-into an application, a server, or the application delivery system, such asCitrix Presentation Server. In one embodiment, the monitoring service198 and/or monitoring agent 197 measures and monitors the duration auser is logged into an application, a server, or the applicationdelivery system 190. In some embodiments, the monitoring service 198and/or monitoring agent 197 measures and monitors active and inactivesession counts for an application, server or application delivery systemsession. In yet another embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors user session latency.

In yet further embodiments, the monitoring service 198 and/or monitoringagent 197 measures and monitors measures and monitors any type and formof server metrics. In one embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors metrics related to systemmemory, CPU usage, and disk storage. In another embodiment, themonitoring service 198 and/or monitoring agent 197 measures and monitorsmetrics related to page faults, such as page faults per second. In otherembodiments, the monitoring service 198 and/or monitoring agent 197measures and monitors round-trip time metrics. In yet anotherembodiment, the monitoring service 198 and/or monitoring agent 197measures and monitors metrics related to application crashes, errorsand/or hangs.

In some embodiments, the monitoring service 198 and monitoring agent 198includes any of the product embodiments referred to as EdgeSightmanufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. In anotherembodiment, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the product embodiments referred to asthe TrueView product suite manufactured by the Symphoniq Corporation ofPalo Alto, Calif. In one embodiment, the performance monitoring service198 and/or monitoring agent 198 includes any portion of the productembodiments referred to as the TeaLeaf CX product suite manufactured bythe TeaLeaf Technology Inc. of San Francisco, Calif. In otherembodiments, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the business service managementproducts, such as the BMC Performance Manager and Patrol products,manufactured by BMC Software, Inc. of Houston, Tex.

The client 102, server 106, and appliance 200 may be deployed as and/orexecuted on any type and form of computing device, such as a computer,network device or appliance capable of communicating on any type andform of network and performing the operations described herein. FIGS. 1Eand 1F depict block diagrams of a computing device 100 useful forpracticing an embodiment of the client 102, server 106 or appliance 200.As shown in FIGS. 1E and 1F, each computing device 100 includes acentral processing unit 101, and a main memory unit 122. As shown inFIG. 1E, a computing device 100 may include a visual display device 124,a keyboard 126 and/or a pointing device 127, such as a mouse. Eachcomputing device 100 may also include additional optional elements, suchas one or more input/output devices 130 a-130 b (generally referred tousing reference numeral 130), and a cache memory 140 in communicationwith the central processing unit 101.

The central processing unit 101 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Inmany embodiments, the central processing unit is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 101, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), BurstExtended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1E, the processor 101communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1F depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1F the main memory 122 maybe DRDRAM.

FIG. 1F depicts an embodiment in which the main processor 101communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 101 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1F, the processor 101 communicates with variousI/O devices 130 via a local system bus 150. Various busses may be usedto connect the central processing unit 101 to any of the I/O devices130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 101 may use an Advanced Graphics Port (AGP) to communicatewith the display 124. FIG. 1F depicts an embodiment of a computer 100 inwhich the main processor 101 communicates directly with I/O device 130 bvia HyperTransport, Rapid I/O, or InfiniBand. FIG. 1F also depicts anembodiment in which local busses and direct communication are mixed: theprocessor 101 communicates with I/O device 130 b using a localinterconnect bus while communicating with I/O device 130 a directly.

The computing device 100 may support any suitable installation device116, such as a floppy disk drive for receiving floppy disks such as3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive,a DVD-ROM drive, tape drives of various formats, USB device, hard-driveor any other device suitable for installing software and programs suchas any client agent 120, or portion thereof. The computing device 100may further comprise a storage device 128, such as one or more hard diskdrives or redundant arrays of independent disks, for storing anoperating system and other related software, and for storing applicationsoftware programs such as any program related to the client agent 120.Optionally, any of the installation devices 116 could also be used asthe storage device 128. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX®, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to a Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (e.g., 802.11,T1, T3, 56 kb, X.25), broadband connections (e.g., ISDN, Frame Relay,ATM), wireless connections, or some combination of any or all of theabove. The network interface 118 may comprise a built-in networkadapter, network interface card, PCMCIA network card, card bus networkadapter, wireless network adapter, USB network adapter, modem or anyother device suitable for interfacing the computing device 100 to anytype of network capable of communication and performing the operationsdescribed herein. A wide variety of I/O devices 130 a-130 n may bepresent in the computing device 100. Input devices include keyboards,mice, trackpads, trackballs, microphones, and drawing tablets. Outputdevices include video displays, speakers, inkjet printers, laserprinters, and dye-sublimation printers. The I/O devices 130 may becontrolled by an I/O controller 123 as shown in FIG. 1E. The I/Ocontroller may control one or more I/O devices such as a keyboard 126and a pointing device 127, e.g., a mouse or optical pen. Furthermore, anI/O device may also provide storage 128 and/or an installation medium116 for the computing device 100. In still other embodiments, thecomputing device 100 may provide USB connections to receive handheld USBstorage devices such as the USB Flash Drive line of devices manufacturedby Twintech Industry, Inc. of Los Alamitos, California.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 betweenthe system bus 150 and an external communication bus, such as a USB bus,an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, aFireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, aGigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, aSuper HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus,or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1E and 1F typicallyoperate under the control of operating systems, which control schedulingof tasks and access to system resources. The computing device 100 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any real-time operatingsystem, any open source operating system, any proprietary operatingsystem, any operating systems for mobile computing devices, or any otheroperating system capable of running on the computing device andperforming the operations described herein. Typical operating systemsinclude: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT3.51, WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which aremanufactured by Microsoft Corporation of Redmond, Wash.; MacOS,manufactured by Apple Computer of Cupertino, California; OS/2,manufactured by International Business Machines of Armonk, N.Y.; andLinux, a freely-available operating system distributed by Caldera Corp.of Salt Lake City, Utah, or any type and/or form of a Unix operatingsystem, among others.

In other embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment the computer 100 is a Treo 180,270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In thisembodiment, the Treo smart phone is operated under the control of thePalmOS operating system and includes a stylus input device as well as afive-way navigator device. Moreover, the computing device 100 can be anyworkstation, desktop computer, laptop or notebook computer, server,handheld computer, mobile telephone, any other computer, or other formof computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

As shown in FIG. 1G, the computing device 100 may comprise multipleprocessors and may provide functionality for simultaneous execution ofinstructions or for simultaneous execution of one instruction on morethan one piece of data. In some embodiments, the computing device 100may comprise a parallel processor with one or more cores. In one ofthese embodiments, the computing device 100 is a shared memory paralleldevice, with multiple processors and/or multiple processor cores,accessing all available memory as a single global address space. Inanother of these embodiments, the computing device 100 is a distributedmemory parallel device with multiple processors each accessing localmemory only. In still another of these embodiments, the computing device100 has both some memory which is shared and some memory which can onlybe accessed by particular processors or subsets of processors. In stilleven another of these embodiments, the computing device 100, such as amulti-core microprocessor, combines two or more independent processorsinto a single package, often a single integrated circuit (IC). In yetanother of these embodiments, the computing device 100 includes a chiphaving a CELL BROADBAND ENGINE architecture and including a Powerprocessor element and a plurality of synergistic processing elements,the Power processor element and the plurality of synergistic processingelements linked together by an internal high speed bus, which may bereferred to as an element interconnect bus.

In some embodiments, the processors provide functionality for executionof a single instruction simultaneously on multiple pieces of data(SIMD). In other embodiments, the processors provide functionality forexecution of multiple instructions simultaneously on multiple pieces ofdata (MIMD). In still other embodiments, the processor may use anycombination of SIMD and MIMD cores in a single device.

In some embodiments, the computing device 100 may comprise a graphicsprocessing unit. In one of these embodiments, depicted in FIG. 1H, thecomputing device 100 includes at least one central processing unit 101and at least one graphics processing unit. In another of theseembodiments, the computing device 100 includes at least one parallelprocessing unit and at least one graphics processing unit. In stillanother of these embodiments, the computing device 100 includes aplurality of processing units of any type, one of the plurality ofprocessing units comprising a graphics processing unit.

In some embodiments, a first computing device 100 a executes anapplication on behalf of a user of a client computing device 100 b. Inother embodiments, a computing device 100 a executes a virtual machine,which provides an execution session within which applications execute onbehalf of a user or a client computing devices 100 b. In one of theseembodiments, the execution session is a hosted desktop session. Inanother of these embodiments, the computing device 100 executes aterminal services session. The terminal services session may provide ahosted desktop environment. In still another of these embodiments, theexecution session provides access to a computing environment, which maycomprise one or more of: an application, a plurality of applications, adesktop application, and a desktop session in which one or moreapplications may execute.

B. Appliance Architecture

FIG. 2A illustrates an example embodiment of the appliance 200. Thearchitecture of the appliance 200 in FIG. 2A is provided by way ofillustration only and is not intended to be limiting. As shown in FIG.2, appliance 200 comprises a hardware layer 206 and a software layerdivided into a user space 202 and a kernel space 204.

Hardware layer 206 provides the hardware elements upon which programsand services within kernel space 204 and user space 202 are executed.Hardware layer 206 also provides the structures and elements which allowprograms and services within kernel space 204 and user space 202 tocommunicate data both internally and externally with respect toappliance 200. As shown in FIG. 2, the hardware layer 206 includes aprocessing unit 262 for executing software programs and services, amemory 264 for storing software and data, network ports 266 fortransmitting and receiving data over a network, and an encryptionprocessor 260 for performing functions related to Secure Sockets Layerprocessing of data transmitted and received over the network. In someembodiments, the central processing unit 262 may perform the functionsof the encryption processor 260 in a single processor. Additionally, thehardware layer 206 may comprise multiple processors for each of theprocessing unit 262 and the encryption processor 260. The processor 262may include any of the processors 101 described above in connection withFIGS. 1E and 1F. For example, in one embodiment, the appliance 200comprises a first processor 262 and a second processor 262′. In otherembodiments, the processor 262 or 262′ comprises a multi-core processor.

Although the hardware layer 206 of appliance 200 is generallyillustrated with an encryption processor 260, processor 260 may be aprocessor for performing functions related to any encryption protocol,such as the Secure Socket Layer (SSL) or Transport Layer Security (TLS)protocol. In some embodiments, the processor 260 may be a generalpurpose processor (GPP), and in further embodiments, may have executableinstructions for performing processing of any security related protocol.

Although the hardware layer 206 of appliance 200 is illustrated withcertain elements in FIG. 2, the hardware portions or components ofappliance 200 may comprise any type and form of elements, hardware orsoftware, of a computing device, such as the computing device 100illustrated and discussed herein in conjunction with FIGS. 1E and 1F. Insome embodiments, the appliance 200 may comprise a server, gateway,router, switch, bridge or other type of computing or network device, andhave any hardware and/or software elements associated therewith.

The operating system of appliance 200 allocates, manages, or otherwisesegregates the available system memory into kernel space 204 and userspace 204. In example software architecture 200, the operating systemmay be any type and/or form of Unix operating system although theinvention is not so limited. As such, the appliance 200 can be runningany operating system such as any of the versions of the Microsoft®Windows operating systems, the different releases of the Unix and Linuxoperating systems, any version of the Mac OS® for Macintosh computers,any embedded operating system, any network operating system, anyreal-time operating system, any open source operating system, anyproprietary operating system, any operating systems for mobile computingdevices or network devices, or any other operating system capable ofrunning on the appliance 200 and performing the operations describedherein.

The kernel space 204 is reserved for running the kernel 230, includingany device drivers, kernel extensions or other kernel related software.As known to those skilled in the art, the kernel 230 is the core of theoperating system, and provides access, control, and management ofresources and hardware-related elements of the application 104. Inaccordance with an embodiment of the appliance 200, the kernel space 204also includes a number of network services or processes working inconjunction with a cache manager 232, sometimes also referred to as theintegrated cache, the benefits of which are described in detail furtherherein. Additionally, the embodiment of the kernel 230 will depend onthe embodiment of the operating system installed, configured, orotherwise used by the device 200.

In one embodiment, the device 200 comprises one network stack 267, suchas a TCP/IP based stack, for communicating with the client 102 and/orthe server 106. In one embodiment, the network stack 267 is used tocommunicate with a first network, such as network 108, and a secondnetwork 110. In some embodiments, the device 200 terminates a firsttransport layer connection, such as a TCP connection of a client 102,and establishes a second transport layer connection to a server 106 foruse by the client 102, e.g., the second transport layer connection isterminated at the appliance 200 and the server 106. The first and secondtransport layer connections may be established via a single networkstack 267. In other embodiments, the device 200 may comprise multiplenetwork stacks, for example 267 and 267′, and the first transport layerconnection may be established or terminated at one network stack 267,and the second transport layer connection on the second network stack267′. For example, one network stack may be for receiving andtransmitting network packet on a first network, and another networkstack for receiving and transmitting network packets on a secondnetwork. In one embodiment, the network stack 267 comprises a buffer 243for queuing one or more network packets for transmission by theappliance 200.

As shown in FIG. 2, the kernel space 204 includes the cache manager 232,a high-speed layer 2-7 integrated packet engine 240, an encryptionengine 234, a policy engine 236 and multi-protocol compression logic238. Running these components or processes 232, 240, 234, 236 and 238 inkernel space 204 or kernel mode instead of the user space 202 improvesthe performance of each of these components, alone and in combination.Kernel operation means that these components or processes 232, 240, 234,236 and 238 run in the core address space of the operating system of thedevice 200. For example, running the encryption engine 234 in kernelmode improves encryption performance by moving encryption and decryptionoperations to the kernel, thereby reducing the number of transitionsbetween the memory space or a kernel thread in kernel mode and thememory space or a thread in user mode. For example, data obtained inkernel mode may not need to be passed or copied to a process or threadrunning in user mode, such as from a kernel level data structure to auser level data structure. In another aspect, the number of contextswitches between kernel mode and user mode are also reduced.Additionally, synchronization of and communications between any of thecomponents or processes 232, 240, 235, 236 and 238 can be performed moreefficiently in the kernel space 204.

In some embodiments, any portion of the components 232, 240, 234, 236and 238 may run or operate in the kernel space 204, while other portionsof these components 232, 240, 234, 236 and 238 may run or operate inuser space 202. In one embodiment, the appliance 200 uses a kernel-leveldata structure providing access to any portion of one or more networkpackets, for example, a network packet comprising a request from aclient 102 or a response from a server 106. In some embodiments, thekernel-level data structure may be obtained by the packet engine 240 viaa transport layer driver interface or filter to the network stack 267.The kernel-level data structure may comprise any interface and/or dataaccessible via the kernel space 204 related to the network stack 267,network traffic or packets received or transmitted by the network stack267. In other embodiments, the kernel-level data structure may be usedby any of the components or processes 232, 240, 234, 236 and 238 toperform the desired operation of the component or process. In oneembodiment, a component 232, 240, 234, 236 and 238 is running in kernelmode 204 when using the kernel-level data structure, while in anotherembodiment, the component 232, 240, 234, 236 and 238 is running in usermode when using the kernel-level data structure. In some embodiments,the kernel-level data structure may be copied or passed to a secondkernel-level data structure, or any desired user-level data structure.

The cache manager 232 may comprise software, hardware or any combinationof software and hardware to provide cache access, control and managementof any type and form of content, such as objects or dynamicallygenerated objects served by the originating servers 106. The data,objects or content processed and stored by the cache manager 232 maycomprise data in any format, such as a markup language, or communicatedvia any protocol. In some embodiments, the cache manager 232 duplicatesoriginal data stored elsewhere or data previously computed, generated ortransmitted, in which the original data may require longer access timeto fetch, compute or otherwise obtain relative to reading a cache memoryelement. Once the data is stored in the cache memory element, future usecan be made by accessing the cached copy rather than refetching orrecomputing the original data, thereby reducing the access time. In someembodiments, the cache memory element may comprise a data object inmemory 264 of device 200. In other embodiments, the cache memory elementmay comprise memory having a faster access time than memory 264. Inanother embodiment, the cache memory element may comprise any type andform of storage element of the device 200, such as a portion of a harddisk. In some embodiments, the processing unit 262 may provide cachememory for use by the cache manager 232. In yet further embodiments, thecache manager 232 may use any portion and combination of memory,storage, or the processing unit for caching data, objects, and othercontent.

Furthermore, the cache manager 232 includes any logic, functions, rules,or operations to perform any embodiments of the techniques of theappliance 200 described herein. For example, the cache manager 232includes logic or functionality to invalidate objects based on theexpiration of an invalidation time period or upon receipt of aninvalidation command from a client 102 or server 106. In someembodiments, the cache manager 232 may operate as a program, service,process or task executing in the kernel space 204, and in otherembodiments, in the user space 202. In one embodiment, a first portionof the cache manager 232 executes in the user space 202 while a secondportion executes in the kernel space 204. In some embodiments, the cachemanager 232 can comprise any type of general purpose processor (GPP), orany other type of integrated circuit, such as a Field Programmable GateArray (FPGA), Programmable Logic Device (PLD), or Application SpecificIntegrated Circuit (ASIC).

The policy engine 236 may include, for example, an intelligentstatistical engine or other programmable application(s). In oneembodiment, the policy engine 236 provides a configuration mechanism toallow a user to identify, specify, define or configure a caching policy.Policy engine 236, in some embodiments, also has access to memory tosupport data structures such as lookup tables or hash tables to enableuser-selected caching policy decisions. In other embodiments, the policyengine 236 may comprise any logic, rules, functions or operations todetermine and provide access, control and management of objects, data orcontent being cached by the appliance 200 in addition to access, controland management of security, network traffic, network access, compressionor any other function or operation performed by the appliance 200.Further examples of specific caching policies are further describedherein.

The encryption engine 234 comprises any logic, business rules, functionsor operations for handling the processing of any security relatedprotocol, such as SSL or TLS, or any function related thereto. Forexample, the encryption engine 234 encrypts and decrypts networkpackets, or any portion thereof, communicated via the appliance 200. Theencryption engine 234 may also setup or establish SSL or TLS connectionson behalf of the client 102 a-102 n, server 106 a-106 n, or appliance200. As such, the encryption engine 234 provides offloading andacceleration of SSL processing. In one embodiment, the encryption engine234 uses a tunneling protocol to provide a virtual private networkbetween a client 102 a-102 n and a server 106 a-106 n. In someembodiments, the encryption engine 234 is in communication with theEncryption processor 260. In other embodiments, the encryption engine234 comprises executable instructions running on the Encryptionprocessor 260.

The multi-protocol compression engine 238 comprises any logic, businessrules, function or operations for compressing one or more protocols of anetwork packet, such as any of the protocols used by the network stack267 of the device 200. In one embodiment, multi-protocol compressionengine 238 compresses bi-directionally between clients 102 a-102 n andservers 106 a-106 n any TCP/IP based protocol, including MessagingApplication Programming Interface (MAPI) (email), File Transfer Protocol(FTP), HyperText Transfer Protocol (HTTP), Common Internet File System(CIFS) protocol (file transfer), Independent Computing Architecture(ICA) protocol, Remote Desktop Protocol (RDP), Wireless ApplicationProtocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol.In other embodiments, multi-protocol compression engine 238 providescompression of Hypertext Markup Language (HTML) based protocols and insome embodiments, provides compression of any markup languages, such asthe Extensible Markup Language (XML). In one embodiment, themulti-protocol compression engine 238 provides compression of anyhigh-performance protocol, such as any protocol designed for appliance200 to appliance 200 communications. In another embodiment, themulti-protocol compression engine 238 compresses any payload of or anycommunication using a modified transport control protocol, such asTransaction TCP (T/TCP), TCP with selection acknowledgements (TCP-SACK),TCP with large windows (TCP-LW), a congestion prediction protocol suchas the TCP-Vegas protocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 acceleratesperformance for users accessing applications via desktop clients, e.g.,Microsoft Outlook and non-Web thin clients, such as any client launchedby popular enterprise applications like Oracle, SAP and Siebel, and evenmobile clients, such as the Pocket PC. In some embodiments, themulti-protocol compression engine 238 by executing in the kernel mode204 and integrating with packet processing engine 240 accessing thenetwork stack 267 is able to compress any of the protocols carried bythe TCP/IP protocol, such as any application layer protocol.

High speed layer 2-7 integrated packet engine 240, also generallyreferred to as a packet processing engine or packet engine, isresponsible for managing the kernel-level processing of packets receivedand transmitted by appliance 200 via network ports 266. The high speedlayer 2-7 integrated packet engine 240 may comprise a buffer for queuingone or more network packets during processing, such as for receipt of anetwork packet or transmission of a network packet. Additionally, thehigh speed layer 2-7 integrated packet engine 240 is in communicationwith one or more network stacks 267 to send and receive network packetsvia network ports 266. The high speed layer 2-7 integrated packet engine240 works in conjunction with encryption engine 234, cache manager 232,policy engine 236 and multi-protocol compression logic 238. Inparticular, encryption engine 234 is configured to perform SSLprocessing of packets, policy engine 236 is configured to performfunctions related to traffic management such as request-level contentswitching and request-level cache redirection, and multi-protocolcompression logic 238 is configured to perform functions related tocompression and decompression of data.

The high speed layer 2-7 integrated packet engine 240 includes a packetprocessing timer 242. In one embodiment, the packet processing timer 242provides one or more time intervals to trigger the processing ofincoming, i.e., received, or outgoing, i.e., transmitted, networkpackets. In some embodiments, the high speed layer 2-7 integrated packetengine 240 processes network packets responsive to the timer 242. Thepacket processing timer 242 provides any type and form of signal to thepacket engine 240 to notify, trigger, or communicate a time relatedevent, interval or occurrence. In many embodiments, the packetprocessing timer 242 operates in the order of milliseconds, such as forexample 100 ms, 50 ms or 25 ms. For example, in some embodiments, thepacket processing timer 242 provides time intervals or otherwise causesa network packet to be processed by the high speed layer 2-7 integratedpacket engine 240 at a 10 ms time interval, while in other embodiments,at a 5 ms time interval, and still yet in further embodiments, as shortas a 3, 2, or 1 ms time interval. The high speed layer 2-7 integratedpacket engine 240 may be interfaced, integrated or in communication withthe encryption engine 234, cache manager 232, policy engine 236 andmulti-protocol compression engine 238 during operation. As such, any ofthe logic, functions, or operations of the encryption engine 234, cachemanager 232, policy engine 236 and multi-protocol compression logic 238may be performed responsive to the packet processing timer 242 and/orthe packet engine 240. Therefore, any of the logic, functions, oroperations of the encryption engine 234, cache manager 232, policyengine 236 and multi-protocol compression logic 238 may be performed atthe granularity of time intervals provided via the packet processingtimer 242, for example, at a time interval of less than or equal to 10ms. For example, in one embodiment, the cache manager 232 may performinvalidation of any cached objects responsive to the high speed layer2-7 integrated packet engine 240 and/or the packet processing timer 242.In another embodiment, the expiry or invalidation time of a cachedobject can be set to the same order of granularity as the time intervalof the packet processing timer 242, such as at every 10 ms.

In contrast to kernel space 204, user space 202 is the memory area orportion of the operating system used by user mode applications orprograms otherwise running in user mode. A user mode application may notaccess kernel space 204 directly and uses service calls in order toaccess kernel services. As shown in FIG. 2, user space 202 of appliance200 includes a graphical user interface (GUI) 210, a command lineinterface (CLI) 212, shell services 214, health monitoring program 216,and daemon services 218. GUI 210 and CLI 212 provide a means by which asystem administrator or other user can interact with and control theoperation of appliance 200, such as via the operating system of theappliance 200. The GUI 210 or CLI 212 can comprise code running in userspace 202 or kernel space 204. The GUI 210 may be any type and form ofgraphical user interface and may be presented via text, graphical orotherwise, by any type of program or application, such as a browser. TheCLI 212 may be any type and form of command line or text-basedinterface, such as a command line provided by the operating system. Forexample, the CLI 212 may comprise a shell, which is a tool to enableusers to interact with the operating system. In some embodiments, theCLI 212 may be provided via a bash, csh, tcsh, or ksh type shell. Theshell services 214 comprises the programs, services, tasks, processes orexecutable instructions to support interaction with the appliance 200 oroperating system by a user via the GUI 210 and/or CLI 212.

Health monitoring program 216 is used to monitor, check, report andensure that network systems are functioning properly and that users arereceiving requested content over a network. Health monitoring program216 comprises one or more programs, services, tasks, processes orexecutable instructions to provide logic, rules, functions or operationsfor monitoring any activity of the appliance 200. In some embodiments,the health monitoring program 216 intercepts and inspects any networktraffic passed via the appliance 200. In other embodiments, the healthmonitoring program 216 interfaces by any suitable means and/ormechanisms with one or more of the following: the encryption engine 234,cache manager 232, policy engine 236, multi-protocol compression logic238, packet engine 240, daemon services 218, and shell services 214. Assuch, the health monitoring program 216 may call any applicationprogramming interface (API) to determine a state, status, or health ofany portion of the appliance 200. For example, the health monitoringprogram 216 may ping or send a status inquiry on a periodic basis tocheck if a program, process, service or task is active and currentlyrunning. In another example, the health monitoring program 216 may checkany status, error or history logs provided by any program, process,service or task to determine any condition, status or error with anyportion of the appliance 200.

Daemon services 218 are programs that run continuously or in thebackground and handle periodic service requests received by appliance200. In some embodiments, a daemon service may forward the requests toother programs or processes, such as another daemon service 218 asappropriate. As known to those skilled in the art, a daemon service 218may run unattended to perform continuous or periodic system widefunctions, such as network control, or to perform any desired task. Insome embodiments, one or more daemon services 218 run in the user space202, while in other embodiments, one or more daemon services 218 run inthe kernel space.

Referring now to FIG. 2B, another embodiment of the appliance 200 isdepicted. In brief overview, the appliance 200 provides one or more ofthe following services, functionality or operations: SSL VPNconnectivity 280, switching/load balancing 284, Domain Name Serviceresolution 286, acceleration 288 and an application firewall 290 forcommunications between one or more clients 102 and one or more servers106. Each of the servers 106 may provide one or more network relatedservices 270 a-270 n (referred to as services 270). For example, aserver 106 may provide an http service 270. The appliance 200 comprisesone or more virtual servers or virtual internet protocol servers,referred to as a vServer, VIP server, or just VIP 275 a-275 n (alsoreferred herein as vServer 275). The vServer 275 receives, intercepts orotherwise processes communications between a client 102 and a server 106in accordance with the configuration and operations of the appliance200.

The vServer 275 may comprise software, hardware or any combination ofsoftware and hardware. The vServer 275 may comprise any type and form ofprogram, service, task, process or executable instructions operating inuser mode 202, kernel mode 204 or any combination thereof in theappliance 200. The vServer 275 includes any logic, functions, rules, oroperations to perform any embodiments of the techniques describedherein, such as SSL VPN 280, switching/load balancing 284, Domain NameService resolution 286, acceleration 288 and an application firewall290. In some embodiments, the vServer 275 establishes a connection to aservice 270 of a server 106. The service 275 may comprise any program,application, process, task or set of executable instructions capable ofconnecting to and communicating to the appliance 200, client 102 orvServer 275. For example, the service 275 may comprise a web server,http server, ftp, email or database server. In some embodiments, theservice 270 is a daemon process or network driver for listening,receiving and/or sending communications for an application, such asemail, database or an enterprise application. In some embodiments, theservice 270 may communicate on a specific IP address, or IP address andport.

In some embodiments, the vServer 275 applies one or more policies of thepolicy engine 236 to network communications between the client 102 andserver 106. In one embodiment, the policies are associated with avServer 275. In another embodiment, the policies are based on a user, ora group of users. In yet another embodiment, a policy is global andapplies to one or more vServers 275 a-275 n, and any user or group ofusers communicating via the appliance 200. In some embodiments, thepolicies of the policy engine have conditions upon which the policy isapplied based on any content of the communication, such as internetprotocol address, port, protocol type, header or fields in a packet, orthe context of the communication, such as user, group of the user,vServer 275, transport layer connection, and/or identification orattributes of the client 102 or server 106.

In other embodiments, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to access the computingenvironment 15, application, and/or data file from a server 106. Inanother embodiment, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to have the application deliverysystem 190 deliver one or more of the computing environment 15,application, and/or data file. In yet another embodiment, the appliance200 establishes a VPN or SSL VPN connection based on the policy engine's236 authentication and/or authorization of a remote user or a remoteclient 102. In one embodiment, the appliance 200 controls the flow ofnetwork traffic and communication sessions based on policies of thepolicy engine 236. For example, the appliance 200 may control the accessto a computing environment 15, application or data file based on thepolicy engine 236.

In some embodiments, the vServer 275 establishes a transport layerconnection, such as a TCP or UDP connection with a client 102 via theclient agent 120. In one embodiment, the vServer 275 listens for andreceives communications from the client 102. In other embodiments, thevServer 275 establishes a transport layer connection, such as a TCP orUDP connection with a client server 106. In one embodiment, the vServer275 establishes the transport layer connection to an internet protocoladdress and port of a server 270 running on the server 106. In anotherembodiment, the vServer 275 associates a first transport layerconnection to a client 102 with a second transport layer connection tothe server 106. In some embodiments, a vServer 275 establishes a pool oftransport layer connections to a server 106 and multiplexes clientrequests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides a SSL VPN connection 280between a client 102 and a server 106. For example, a client 102 on afirst network 102 requests to establish a connection to a server 106 ona second network 104′. In some embodiments, the second network 104′ isnot routable from the first network 104. In other embodiments, theclient 102 is on a public network 104 and the server 106 is on a privatenetwork 104′, such as a corporate network. In one embodiment, the clientagent 120 intercepts communications of the client 102 on the firstnetwork 104, encrypts the communications, and transmits thecommunications via a first transport layer connection to the appliance200. The appliance 200 associates the first transport layer connectionon the first network 104 to a second transport layer connection to theserver 106 on the second network 104. The appliance 200 receives theintercepted communication from the client agent 102, decrypts thecommunications, and transmits the communication to the server 106 on thesecond network 104 via the second transport layer connection. The secondtransport layer connection may be a pooled transport layer connection.As such, the appliance 200 provides an end-to-end secure transport layerconnection for the client 102 between the two networks 104, 104′.

In one embodiment, the appliance 200 hosts an intranet internet protocolor IntranetIP 282 address of the client 102 on the virtual privatenetwork 104. The client 102 has a local network identifier, such as aninternet protocol (IP) address and/or host name on the first network104. When connected to the second network 104′ via the appliance 200,the appliance 200 establishes, assigns or otherwise provides anIntranetlIP address 282, which is a network identifier, such as IPaddress and/or host name, for the client 102 on the second network 104′.The appliance 200 listens for and receives on the second or privatenetwork 104′ for any communications directed towards the client 102using the client's established IntranetIP 282. In one embodiment, theappliance 200 acts as or on behalf of the client 102 on the secondprivate network 104. For example, in another embodiment, a vServer 275listens for and responds to communications to the IntranetIP 282 of theclient 102. In some embodiments, if a computing device 100 on the secondnetwork 104′ transmits a request, the appliance 200 processes therequest as if it were the client 102. For example, the appliance 200 mayrespond to a ping to the client's IntranetIP 282. In another example,the appliance may establish a connection, such as a TCP or UDPconnection, with computing device 100 on the second network 104requesting a connection with the client's IntranetIP 282. In someembodiments, the appliance 200 provides one or more of the followingacceleration techniques 288 to communications between the client 102 andserver 106: 1) compression; 2) decompression; 3) Transmission ControlProtocol pooling; 4) Transmission Control Protocol multiplexing; 5)Transmission Control Protocol buffering; and 6) caching. In oneembodiment, the appliance 200 relieves servers 106 of much of theprocessing load caused by repeatedly opening and closing transportlayers connections to clients 102 by opening one or more transport layerconnections with each server 106 and maintaining these connections toallow repeated data accesses by clients via the Internet. This techniqueis referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from aclient 102 to a server 106 via a pooled transport layer connection, theappliance 200 translates or multiplexes communications by modifyingsequence number and acknowledgment numbers at the transport layerprotocol level. This is referred to as “connection multiplexing”. Insome embodiments, no application layer protocol interaction is required.For example, in the case of an in-bound packet (that is, a packetreceived from a client 102), the source network address of the packet ischanged to that of an output port of appliance 200, and the destinationnetwork address is changed to that of the intended server. In the caseof an outbound packet (that is, one received from a server 106), thesource network address is changed from that of the server 106 to that ofan output port of appliance 200 and the destination address is changedfrom that of appliance 200 to that of the requesting client 102. Thesequence numbers and acknowledgment numbers of the packet are alsotranslated to sequence numbers and acknowledgement numbers expected bythe client 102 on the appliance's 200 transport layer connection to theclient 102. In some embodiments, the packet checksum of the transportlayer protocol is recalculated to account for these translations.

In another embodiment, the appliance 200 provides switching orload-balancing functionality 284 for communications between the client102 and server 106. In some embodiments, the appliance 200 distributestraffic and directs client requests to a server 106 based on layer 4 orapplication-layer request data. In one embodiment, although the networklayer or layer 2 of the network packet identifies a destination server106, the appliance 200 determines the server 106 to distribute thenetwork packet by application information and data carried as payload ofthe transport layer packet. In one embodiment, the health monitoringprograms 216 of the appliance 200 monitor the health of servers todetermine the server 106 for which to distribute a client's request. Insome embodiments, if the appliance 200 detects a server 106 is notavailable or has a load over a predetermined threshold, the appliance200 can direct or distribute client requests to another server 106.

In some embodiments, the appliance 200 acts as a Domain Name Service(DNS) resolver or otherwise provides resolution of a DNS request fromclients 102. In some embodiments, the appliance intercepts a DNS requesttransmitted by the client 102. In one embodiment, the appliance 200responds to a client's DNS request with an IP address of or hosted bythe appliance 200. In this embodiment, the client 102 transmits networkcommunication for the domain name to the appliance 200. In anotherembodiment, the appliance 200 responds to a client's DNS request with anIP address of or hosted by a second appliance 200′. In some embodiments,the appliance 200 responds to a client's DNS request with an IP addressof a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 200 provides applicationfirewall functionality 290 for communications between the client 102 andserver 106. In one embodiment, the policy engine 236 provides rules fordetecting and blocking illegitimate requests. In some embodiments, theapplication firewall 290 protects against denial of service (DoS)attacks. In other embodiments, the appliance inspects the content ofintercepted requests to identify and block application-based attacks. Insome embodiments, the rules/policy engine 236 comprises one or moreapplication firewall or security control policies for providingprotections against various classes and types of web or Internet basedvulnerabilities, such as one or more of the following: 1) bufferoverflow, 2) CGI-BIN parameter manipulation, 3) form/hidden fieldmanipulation, 4) forceful browsing, 5) cookie or session poisoning, 6)broken access control list (ACLs) or weak passwords, 7) cross-sitescripting (XSS), 8) command injection, 9) SQL injection, 10) errortriggering sensitive information leak, 11) insecure use of cryptography,12) server misconfiguration, 13) back doors and debug options, 14)website defacement, 15) platform or operating systems vulnerabilities,and 16) zero-day exploits. In an embodiment, the application firewall290 provides HTML form field protection in the form of inspecting oranalyzing the network communication for one or more of the following: 1)required fields are returned, 2) no added field allowed, 3) read-onlyand hidden field enforcement, 4) drop-down list and radio button fieldconformance, and 5) form-field max-length enforcement. In someembodiments, the application firewall 290 ensures cookies are notmodified. In other embodiments, the application firewall 290 protectsagainst forceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall 290 protectsany confidential information contained in the network communication. Theapplication firewall 290 may inspect or analyze any networkcommunication in accordance with the rules or polices of the engine 236to identify any confidential information in any field of the networkpacket. In some embodiments, the application firewall 290 identifies inthe network communication one or more occurrences of a credit cardnumber, password, social security number, name, patient code, contactinformation, and age. The encoded portion of the network communicationmay comprise these occurrences or the confidential information. Based onthese occurrences, in one embodiment, the application firewall 290 maytake a policy action on the network communication, such as preventtransmission of the network communication. In another embodiment, theapplication firewall 290 may rewrite, remove or otherwise mask suchidentified occurrence or confidential information.

Still referring to FIG. 2B, the appliance 200 may include a performancemonitoring agent 197 as discussed above in conjunction with FIG. 1D. Inone embodiment, the appliance 200 receives the monitoring agent 197 fromthe monitoring service 198 or monitoring server 106 as depicted in FIG.1D. In some embodiments, the appliance 200 stores the monitoring agent197 in storage, such as disk, for delivery to any client or server incommunication with the appliance 200. For example, in one embodiment,the appliance 200 transmits the monitoring agent 197 to a client uponreceiving a request to establish a transport layer connection. In otherembodiments, the appliance 200 transmits the monitoring agent 197 uponestablishing the transport layer connection with the client 102. Inanother embodiment, the appliance 200 transmits the monitoring agent 197to the client upon intercepting or detecting a request for a web page.In yet another embodiment, the appliance 200 transmits the monitoringagent 197 to a client or a server in response to a request from themonitoring server 198. In one embodiment, the appliance 200 transmitsthe monitoring agent 197 to a second appliance 200′ or appliance 205.

In other embodiments, the appliance 200 executes the monitoring agent197. In one embodiment, the monitoring agent 197 measures and monitorsthe performance of any application, program, process, service, task orthread executing on the appliance 200. For example, the monitoring agent197 may monitor and measure performance and operation of vServers275A-275N. In another embodiment, the monitoring agent 197 measures andmonitors the performance of any transport layer connections of theappliance 200. In some embodiments, the monitoring agent 197 measuresand monitors the performance of any user sessions traversing theappliance 200. In one embodiment, the monitoring agent 197 measures andmonitors the performance of any virtual private network connectionsand/or sessions traversing the appliance 200, such an SSL VPN session.In still further embodiments, the monitoring agent 197 measures andmonitors the memory, CPU and disk usage and performance of the appliance200. In yet another embodiment, the monitoring agent 197 measures andmonitors the performance of any acceleration technique 288 performed bythe appliance 200, such as SSL offloading, connection pooling andmultiplexing, caching, and compression. In some embodiments, themonitoring agent 197 measures and monitors the performance of any loadbalancing and/or content switching 284 performed by the appliance 200.In other embodiments, the monitoring agent 197 measures and monitors theperformance of application firewall 290 protection and processingperformed by the appliance 200.

C. Client Agent

Referring now to FIG. 3, an embodiment of the client agent 120 isdepicted. The client 102 includes a client agent 120 for establishingand exchanging communications with the appliance 200 and/or server 106via a network 104. In brief overview, the client 102 operates oncomputing device 100 having an operating system with a kernel mode 302and a user mode 303, and a network stack 310 with one or more layers 310a-310 b. The client 102 may have installed and/or execute one or moreapplications. In some embodiments, one or more applications maycommunicate via the network stack 310 to a network 104. One of theapplications, such as a web browser, may also include a first program322. For example, the first program 322 may be used in some embodimentsto install and/or execute the client agent 120, or any portion thereof.The client agent 120 includes an interception mechanism, or interceptor350, for intercepting network communications from the network stack 310from the one or more applications.

The network stack 310 of the client 102 may comprise any type and formof software, or hardware, or any combinations thereof, for providingconnectivity to and communications with a network. In one embodiment,the network stack 310 comprises a software implementation for a networkprotocol suite. The network stack 310 may comprise one or more networklayers, such as any networks layers of the Open Systems Interconnection(OSI) communications model as those skilled in the art recognize andappreciate. As such, the network stack 310 may comprise any type andform of protocols for any of the following layers of the OSI model: 1)physical link layer, 2) data link layer, 3) network layer, 4) transportlayer, 5) session layer, 6) presentation layer, and 7) applicationlayer. In one embodiment, the network stack 310 may comprise a transportcontrol protocol (TCP) over the network layer protocol of the internetprotocol (IP), generally referred to as TCP/IP. In some embodiments, theTCP/IP protocol may be carried over the Ethernet protocol, which maycomprise any of the family of IEEE wide-area-network (WAN) orlocal-area-network (LAN) protocols, such as those protocols covered bythe IEEE 802.3. In some embodiments, the network stack 310 comprises anytype and form of a wireless protocol, such as IEEE 802.11 and/or mobileinternet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may beused, including Messaging Application Programming Interface (MAPI)(email), File Transfer Protocol (FTP), HyperText Transfer Protocol(HTTP), Common Internet File System (CIFS) protocol (file transfer),Independent Computing Architecture (ICA) protocol, Remote DesktopProtocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol,and Voice Over IP (VoIP) protocol. In another embodiment, the networkstack 310 comprises any type and form of transport control protocol,such as a modified transport control protocol, for example a TransactionTCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP withlarge windows (TCP-LW), a congestion prediction protocol such as theTCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments,any type and form of user datagram protocol (UDP), such as UDP over IP,may be used by the network stack 310, such as for voice communicationsor real-time data communications.

Furthermore, the network stack 310 may include one or more networkdrivers supporting the one or more layers, such as a TCP driver or anetwork layer driver. The network drivers may be included as part of theoperating system of the computing device 100 or as part of any networkinterface cards or other network access components of the computingdevice 100. In some embodiments, any of the network drivers of thenetwork stack 310 may be customized, modified or adapted to provide acustom or modified portion of the network stack 310 in support of any ofthe techniques described herein. In other embodiments, the accelerationprogram 302 is designed and constructed to operate with or work inconjunction with the network stack 310 installed or otherwise providedby the operating system of the client 102.

The network stack 310 comprises any type and form of interfaces forreceiving, obtaining, providing or otherwise accessing any informationand data related to network communications of the client 102. In oneembodiment, an interface to the network stack 310 comprises anapplication programming interface (API). The interface may also compriseany function call, hooking or filtering mechanism, event or call backmechanism, or any type of interfacing technique. The network stack 310via the interface may receive or provide any type and form of datastructure, such as an object, related to functionality or operation ofthe network stack 310. For example, the data structure may compriseinformation and data related to a network packet or one or more networkpackets. In some embodiments, the data structure comprises a portion ofthe network packet processed at a protocol layer of the network stack310, such as a network packet of the transport layer. In someembodiments, the data structure 325 comprises a kernel-level datastructure, while in other embodiments, the data structure 325 comprisesa user-mode data structure. A kernel-level data structure may comprise adata structure obtained or related to a portion of the network stack 310operating in kernel-mode 302, or a network driver or other softwarerunning in kernel-mode 302, or any data structure obtained or receivedby a service, process, task, thread or other executable instructionsrunning or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 310 may execute oroperate in kernel-mode 302, for example, the data link or network layer,while other portions execute or operate in user-mode 303, such as anapplication layer of the network stack 310. For example, a first portion310 a of the network stack may provide user-mode access to the networkstack 310 to an application while a second portion 310 a of the networkstack 310 provides access to a network. In some embodiments, a firstportion 310 a of the network stack may comprise one or more upper layersof the network stack 310, such as any of layers 5-7. In otherembodiments, a second portion 310 b of the network stack 310 comprisesone or more lower layers, such as any of layers 1-4. Each of the firstportion 310 a and second portion 310 b of the network stack 310 maycomprise any portion of the network stack 310, at any one or morenetwork layers, in user-mode 203, kernel-mode, 202, or combinationsthereof, or at any portion of a network layer or interface point to anetwork layer or any portion of or interface point to the user-mode 203and kernel-mode 203.

The interceptor 350 may comprise software, hardware, or any combinationof software and hardware. In one embodiment, the interceptor 350intercept a network communication at any point in the network stack 310,and redirects or transmits the network communication to a destinationdesired, managed or controlled by the interceptor 350 or client agent120. For example, the interceptor 350 may intercept a networkcommunication of a network stack 310 of a first network and transmit thenetwork communication to the appliance 200 for transmission on a secondnetwork 104. In some embodiments, the interceptor 350 comprises any typeinterceptor 350 comprises a driver, such as a network driver constructedand designed to interface and work with the network stack 310. In someembodiments, the client agent 120 and/or interceptor 350 operates at oneor more layers of the network stack 310, such as at the transport layer.In one embodiment, the interceptor 350 comprises a filter driver,hooking mechanism, or any form and type of suitable network driverinterface that interfaces to the transport layer of the network stack,such as via the transport driver interface (TDI). In some embodiments,the interceptor 350 interfaces to a first protocol layer, such as thetransport layer and another protocol layer, such as any layer above thetransport protocol layer, for example, an application protocol layer. Inone embodiment, the interceptor 350 may comprise a driver complying withthe Network Driver Interface Specification (NDIS), or a NDIS driver. Inanother embodiment, the interceptor 350 may comprise a mini-filter or amini-port driver. In one embodiment, the interceptor 350, or portionthereof, operates in kernel-mode 202. In another embodiment, theinterceptor 350, or portion thereof, operates in user-mode 203. In someembodiments, a portion of the interceptor 350 operates in kernel-mode202 while another portion of the interceptor 350 operates in user-mode203. In other embodiments, the client agent 120 operates in user-mode203 but interfaces via the interceptor 350 to a kernel-mode driver,process, service, task or portion of the operating system, such as toobtain a kernel-level data structure 225. In further embodiments, theinterceptor 350 is a user-mode application or program, such asapplication.

In one embodiment, the interceptor 350 intercepts any transport layerconnection requests. In these embodiments, the interceptor 350 executetransport layer application programming interface (API) calls to set thedestination information, such as destination IP address and/or port to adesired location for the location. In this manner, the interceptor 350intercepts and redirects the transport layer connection to a IP addressand port controlled or managed by the interceptor 350 or client agent120. In one embodiment, the interceptor 350 sets the destinationinformation for the connection to a local IP address and port of theclient 102 on which the client agent 120 is listening. For example, theclient agent 120 may comprise a proxy service listening on a local IPaddress and port for redirected transport layer communications. In someembodiments, the client agent 120 then communicates the redirectedtransport layer communication to the appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain NameService (DNS) request. In one embodiment, the client agent 120 and/orinterceptor 350 resolves the DNS request. In another embodiment, theinterceptor transmits the intercepted DNS request to the appliance 200for DNS resolution. In one embodiment, the appliance 200 resolves theDNS request and communicates the DNS response to the client agent 120.In some embodiments, the appliance 200 resolves the DNS request viaanother appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may comprise two agents120 and 120′. In one embodiment, a first agent 120 may comprise aninterceptor 350 operating at the network layer of the network stack 310.In some embodiments, the first agent 120 intercepts network layerrequests such as Internet Control Message Protocol (ICMP) requests(e.g., ping and traceroute). In other embodiments, the second agent 120′may operate at the transport layer and intercept transport layercommunications. In some embodiments, the first agent 120 interceptscommunications at one layer of the network stack 210 and interfaces withor communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interfacewith a protocol layer in a manner transparent to any other protocollayer of the network stack 310. For example, in one embodiment, theinterceptor 350 operates or interfaces with the transport layer of thenetwork stack 310 transparently to any protocol layer below thetransport layer, such as the network layer, and any protocol layer abovethe transport layer, such as the session, presentation or applicationlayer protocols. This allows the other protocol layers of the networkstack 310 to operate as desired and without modification for using theinterceptor 350. As such, the client agent 120 and/or interceptor 350can interface with the transport layer to secure, optimize, accelerate,route or load-balance any communications provided via any protocolcarried by the transport layer, such as any application layer protocolover TCP/IP.

Furthermore, the client agent 120 and/or interceptor may operate at orinterface with the network stack 310 in a manner transparent to anyapplication, a user of the client 102, and any other computing device,such as a server, in communications with the client 102. The clientagent 120 and/or interceptor 350 may be installed and/or executed on theclient 102 in a manner without modification of an application. In someembodiments, the user of the client 102 or a computing device incommunications with the client 102 are not aware of the existence,execution or operation of the client agent 120 and/or interceptor 350.As such, in some embodiments, the client agent 120 and/or interceptor350 is installed, executed, and/or operated transparently to anapplication, user of the client 102, another computing device, such as aserver, or any of the protocol layers above and/or below the protocollayer interfaced to by the interceptor 350.

The client agent 120 includes an acceleration program 302, a streamingclient 306, a collection agent 304, and/or monitoring agent 197. In oneembodiment, the client agent 120 comprises an Independent ComputingArchitecture (ICA) client, or any portion thereof, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla., and is also referred to as anICA client. In some embodiments, the client 120 comprises an applicationstreaming client 306 for streaming an application from a server 106 to aclient 102. In some embodiments, the client agent 120 comprises anacceleration program 302 for accelerating communications between client102 and server 106. In another embodiment, the client agent 120 includesa collection agent 304 for performing end-point detection/scanning andcollecting end-point information for the appliance 200 and/or server106.

In some embodiments, the acceleration program 302 comprises aclient-side acceleration program for performing one or more accelerationtechniques to accelerate, enhance or otherwise improve a client'scommunications with and/or access to a server 106, such as accessing anapplication provided by a server 106. The logic, functions, and/oroperations of the executable instructions of the acceleration program302 may perform one or more of the following acceleration techniques: 1)multi-protocol compression, 2) transport control protocol pooling, 3)transport control protocol multiplexing, 4) transport control protocolbuffering, and 5) caching via a cache manager. Additionally, theacceleration program 302 may perform encryption and/or decryption of anycommunications received and/or transmitted by the client 102. In someembodiments, the acceleration program 302 performs one or more of theacceleration techniques in an integrated manner or fashion.Additionally, the acceleration program 302 can perform compression onany of the protocols, or multiple-protocols, carried as a payload of anetwork packet of the transport layer protocol.

The streaming client 306 comprises an application, program, process,service, task or executable instructions for receiving and executing astreamed application from a server 106. A server 106 may stream one ormore application data files to the streaming client 306 for playing,executing or otherwise causing to be executed the application on theclient 102. In some embodiments, the server 106 transmits a set ofcompressed or packaged application data files to the streaming client306. In some embodiments, the plurality of application files arecompressed and stored on a file server within an archive file such as aCAB, ZIP, SIT, TAR, JAR or other archive. In one embodiment, the server106 decompresses, unpackages or unarchives the application files andtransmits the files to the client 102. In another embodiment, the client102 decompresses, unpackages or unarchives the application files. Thestreaming client 306 dynamically installs the application, or portionthereof, and executes the application. In one embodiment, the streamingclient 306 may be an executable program. In some embodiments, thestreaming client 306 may be able to launch another executable program.

The collection agent 304 comprises an application, program, process,service, task or executable instructions for identifying, obtainingand/or collecting information about the client 102. In some embodiments,the appliance 200 transmits the collection agent 304 to the client 102or client agent 120. The collection agent 304 may be configuredaccording to one or more policies of the policy engine 236 of theappliance. In other embodiments, the collection agent 304 transmitscollected information on the client 102 to the appliance 200. In oneembodiment, the policy engine 236 of the appliance 200 uses thecollected information to determine and provide access, authenticationand authorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-pointdetection and scanning mechanism, which identifies and determines one ormore attributes or characteristics of the client. For example, thecollection agent 304 may identify and determine any one or more of thefollowing client-side attributes: 1) the operating system an/or aversion of an operating system, 2) a service pack of the operatingsystem, 3) a running service, 4) a running process, and 5) a file. Thecollection agent 304 may also identify and determine the presence orversions of any one or more of the following on the client: 1) antivirussoftware, 2) personal firewall software, 3) anti-spam software, and 4)internet security software. The policy engine 236 may have one or morepolicies based on any one or more of the attributes or characteristicsof the client or client-side attributes.

In some embodiments, the client agent 120 includes a monitoring agent197 as discussed in conjunction with FIGS. 1D and 2B. The monitoringagent 197 may be any type and form of script, such as Visual Basic orJava script. In one embodiment, the monitoring agent 197 monitors andmeasures performance of any portion of the client agent 120. Forexample, in some embodiments, the monitoring agent 197 monitors andmeasures performance of the acceleration program 302. In anotherembodiment, the monitoring agent 197 monitors and measures performanceof the streaming client 306. In other embodiments, the monitoring agent197 monitors and measures performance of the collection agent 304. Instill another embodiment, the monitoring agent 197 monitors and measuresperformance of the interceptor 350. In some embodiments, the monitoringagent 197 monitors and measures any resource of the client 102, such asmemory, CPU and disk.

The monitoring agent 197 may monitor and measure performance of anyapplication of the client. In one embodiment, the monitoring agent 197monitors and measures performance of a browser on the client 102. Insome embodiments, the monitoring agent 197 monitors and measuresperformance of any application delivered via the client agent 120. Inother embodiments, the monitoring agent 197 measures and monitors enduser response times for an application, such as web-based or HTTPresponse times. The monitoring agent 197 may monitor and measureperformance of an ICA or RDP client. In another embodiment, themonitoring agent 197 measures and monitors metrics for a user session orapplication session. In some embodiments, monitoring agent 197 measuresand monitors an ICA or RDP session. In one embodiment, the monitoringagent 197 measures and monitors the performance of the appliance 200 inaccelerating delivery of an application and/or data to the client 102.

In some embodiments and still referring to FIG. 3, a first program 322may be used to install and/or execute the client agent 120, or portionthereof, such as the interceptor 350, automatically, silently,transparently, or otherwise. In one embodiment, the first program 322comprises a plugin component, such an ActiveX control or Java control orscript that is loaded into and executed by an application. For example,the first program comprises an ActiveX control loaded and run by a webbrowser application, such as in the memory space or context of theapplication. In another embodiment, the first program 322 comprises aset of executable instructions loaded into and run by the application,such as a browser. In one embodiment, the first program 322 comprises adesigned and constructed program to install the client agent 120. Insome embodiments, the first program 322 obtains, downloads, or receivesthe client agent 120 via the network from another computing device. Inanother embodiment, the first program 322 is an installer program or aplug and play manager for installing programs, such as network drivers,on the operating system of the client 102.

D. Systems and Methods for Providing Virtualized Application DeliveryController

Referring now to FIG. 4A, a block diagram depicts one embodiment of avirtualization environment 400. In brief overview, a computing device100 includes a hypervisor layer, a virtualization layer, and a hardwarelayer. The hypervisor layer includes a hypervisor 401 (also referred toas a virtualization manager) that allocates and manages access to anumber of physical resources in the hardware layer (e.g., theprocessor(s) 421, and disk(s) 428) by at least one virtual machineexecuting in the virtualization layer. The virtualization layer includesat least one operating system 410 and a plurality of virtual resourcesallocated to the at least one operating system 410. Virtual resourcesmay include, without limitation, a plurality of virtual processors 432a, 432 b, 432 c (generally 432), and virtual disks 442 a, 442 b, 442 c(generally 442), as well as virtual resources such as virtual memory andvirtual network interfaces. The plurality of virtual resources and theoperating system 410 may be referred to as a virtual machine 406. Avirtual machine 406 may include a control operating system 405 incommunication with the hypervisor 401 and used to execute applicationsfor managing and configuring other virtual machines on the computingdevice 100.

In greater detail, a hypervisor 401 may provide virtual resources to anoperating system in any manner which simulates the operating systemhaving access to a physical device. A hypervisor 401 may provide virtualresources to any number of guest operating systems 410 a, 410 b(generally 410). In some embodiments, a computing device 100 executesone or more types of hypervisors. In these embodiments, hypervisors maybe used to emulate virtual hardware, partition physical hardware,virtualize physical hardware, and execute virtual machines that provideaccess to computing environments. Hypervisors may include thosemanufactured by VMWare, Inc., of Palo Alto, Calif.; the XEN hypervisor,an open source product whose development is overseen by the open sourceXen.org community; HyperV, VirtualServer or virtual PC hypervisorsprovided by Microsoft, or others. In some embodiments, a computingdevice 100 executing a hypervisor that creates a virtual machineplatform on which guest operating systems may execute is referred to asa host server. In one of these embodiments, for example, the computingdevice 100 is a XEN SERVER provided by Citrix Systems, Inc., of FortLauderdale, Fla.

In some embodiments, a hypervisor 401 executes within an operatingsystem executing on a computing device. In one of these embodiments, acomputing device executing an operating system and a hypervisor 401 maybe said to have a host operating system (the operating system executingon the computing device), and a guest operating system (an operatingsystem executing within a computing resource partition provided by thehypervisor 401). In other embodiments, a hypervisor 401 interactsdirectly with hardware on a computing device, instead of executing on ahost operating system. In one of these embodiments, the hypervisor 401may be said to be executing on “bare metal,” referring to the hardwarecomprising the computing device.

In some embodiments, a hypervisor 401 may create a virtual machine 406a-c (generally 406) in which an operating system 410 executes. In one ofthese embodiments, for example, the hypervisor 401 loads a virtualmachine image to create a virtual machine 406. In another of theseembodiments, the hypervisor 401 executes an operating system 410 withinthe virtual machine 406. In still another of these embodiments, thevirtual machine 406 executes an operating system 410.

In some embodiments, the hypervisor 401 controls processor schedulingand memory partitioning for a virtual machine 406 executing on thecomputing device 100. In one of these embodiments, the hypervisor 401controls the execution of at least one virtual machine 406. In anotherof these embodiments, the hypervisor 401 presents at least one virtualmachine 406 with an abstraction of at least one hardware resourceprovided by the computing device 100. In other embodiments, thehypervisor 401 controls whether and how physical processor capabilitiesare presented to the virtual machine 406.

A control operating system 405 may execute at least one application formanaging and configuring the guest operating systems. In one embodiment,the control operating system 405 may execute an administrativeapplication, such as an application including a user interface providingadministrators with access to functionality for managing the executionof a virtual machine, including functionality for executing a virtualmachine, terminating an execution of a virtual machine, or identifying atype of physical resource for allocation to the virtual machine. Inanother embodiment, the hypervisor 401 executes the control operatingsystem 405 within a virtual machine 406 created by the hypervisor 401.In still another embodiment, the control operating system 405 executesin a virtual machine 406 that is authorized to directly access physicalresources on the computing device 100. In some embodiments, a controloperating system 405 a on a computing device 100 a may exchange datawith a control operating system 405 b on a computing device 100 b, viacommunications between a hypervisor 401 a and a hypervisor 401 b. Inthis way, one or more computing devices 100 may exchange data with oneor more of the other computing devices 100 regarding processors andother physical resources available in a pool of resources. In one ofthese embodiments, this functionality allows a hypervisor to manage apool of resources distributed across a plurality of physical computingdevices. In another of these embodiments, multiple hypervisors manageone or more of the guest operating systems executed on one of thecomputing devices 100.

In one embodiment, the control operating system 405 executes in avirtual machine 406 that is authorized to interact with at least oneguest operating system 410. In another embodiment, a guest operatingsystem 410 communicates with the control operating system 405 via thehypervisor 401 in order to request access to a disk or a network. Instill another embodiment, the guest operating system 410 and the controloperating system 405 may communicate via a communication channelestablished by the hypervisor 401, such as, for example, via a pluralityof shared memory pages made available by the hypervisor 401.

In some embodiments, the control operating system 405 includes a networkback-end driver for communicating directly with networking hardwareprovided by the computing device 100. In one of these embodiments, thenetwork back-end driver processes at least one virtual machine requestfrom at least one guest operating system 110. In other embodiments, thecontrol operating system 405 includes a block back-end driver forcommunicating with a storage element on the computing device 100. In oneof these embodiments, the block back-end driver reads and writes datafrom the storage element based upon at least one request received from aguest operating system 410.

In one embodiment, the control operating system 405 includes a toolsstack 404. In another embodiment, a tools stack 404 providesfunctionality for interacting with the hypervisor 401, communicatingwith other control operating systems 405 (for example, on a secondcomputing device 100 b), or managing virtual machines 406 b, 406 c onthe computing device 100. In another embodiment, the tools stack 404includes customized applications for providing improved managementfunctionality to an administrator of a virtual machine farm. In someembodiments, at least one of the tools stack 404 and the controloperating system 405 include a management API that provides an interfacefor remotely configuring and controlling virtual machines 406 running ona computing device 100. In other embodiments, the control operatingsystem 405 communicates with the hypervisor 401 through the tools stack404.

In one embodiment, the hypervisor 401 executes a guest operating system410 within a virtual machine 406 created by the hypervisor 401. Inanother embodiment, the guest operating system 410 provides a user ofthe computing device 100 with access to resources within a computingenvironment. In still another embodiment, a resource includes a program,an application, a document, a file, a plurality of applications, aplurality of files, an executable program file, a desktop environment, acomputing environment, or other resource made available to a user of thecomputing device 100. In yet another embodiment, the resource may bedelivered to the computing device 100 via a plurality of access methodsincluding, but not limited to, conventional installation directly on thecomputing device 100, delivery to the computing device 100 via a methodfor application streaming, delivery to the computing device 100 ofoutput data generated by an execution of the resource on a secondcomputing device 100′ and communicated to the computing device 100 via apresentation layer protocol, delivery to the computing device 100 ofoutput data generated by an execution of the resource via a virtualmachine executing on a second computing device 100′, or execution from aremovable storage device connected to the computing device 100, such asa USB device, or via a virtual machine executing on the computing device100 and generating output data. In some embodiments, the computingdevice 100 transmits output data generated by the execution of theresource to another computing device 100′.

In one embodiment, the guest operating system 410, in conjunction withthe virtual machine on which it executes, forms a fully-virtualizedvirtual machine which is not aware that it is a virtual machine; such amachine may be referred to as a “Domain U HVM (Hardware Virtual Machine)virtual machine”. In another embodiment, a fully-virtualized machineincludes software emulating a Basic Input/Output System (BIOS) in orderto execute an operating system within the fully-virtualized machine. Instill another embodiment, a fully-virtualized machine may include adriver that provides functionality by communicating with the hypervisor401. In such an embodiment, the driver may be aware that it executeswithin a virtualized environment. In another embodiment, the guestoperating system 410, in conjunction with the virtual machine on whichit executes, forms a paravirtualized virtual machine, which is awarethat it is a virtual machine; such a machine may be referred to as a“Domain U PV virtual machine”. In another embodiment, a paravirtualizedmachine includes additional drivers that a fully-virtualized machinedoes not include. In still another embodiment, the paravirtualizedmachine includes the network back-end driver and the block back-enddriver included in a control operating system 405, as described above.

Referring now to FIG. 4B, a block diagram depicts one embodiment of aplurality of networked computing devices in a system in which at leastone physical host executes a virtual machine. In brief overview, thesystem includes a management component 404 and a hypervisor 401. Thesystem includes a plurality of computing devices 100, a plurality ofvirtual machines 406, a plurality of hypervisors 401, a plurality ofmanagement components referred to variously as tools stacks 404 ormanagement components 404, and a physical resource 421, 428. Theplurality of physical machines 100 may each be provided as computingdevices 100, described above in connection with FIGS. 1E-1H and 4A.

In greater detail, a physical disk 428 is provided by a computing device100 and stores at least a portion of a virtual disk 442. In someembodiments, a virtual disk 442 is associated with a plurality ofphysical disks 428. In one of these embodiments, one or more computingdevices 100 may exchange data with one or more of the other computingdevices 100 regarding processors and other physical resources availablein a pool of resources, allowing a hypervisor to manage a pool ofresources distributed across a plurality of physical computing devices.In some embodiments, a computing device 100 on which a virtual machine406 executes is referred to as a physical host 100 or as a host machine100.

The hypervisor executes on a processor on the computing device 100. Thehypervisor allocates, to a virtual disk, an amount of access to thephysical disk. In one embodiment, the hypervisor 401 allocates an amountof space on the physical disk. In another embodiment, the hypervisor 401allocates a plurality of pages on the physical disk. In someembodiments, the hypervisor provisions the virtual disk 442 as part of aprocess of initializing and executing a virtual machine 450.

In one embodiment, the management component 404 a is referred to as apool management component 404 a. In another embodiment, a managementoperating system 405 a, which may be referred to as a control operatingsystem 405 a, includes the management component. In some embodiments,the management component is referred to as a tools stack. In one ofthese embodiments, the management component is the tools stack 404described above in connection with FIG. 4A. In other embodiments, themanagement component 404 provides a user interface for receiving, from auser such as an administrator, an identification of a virtual machine406 to provision and/or execute. In still other embodiments, themanagement component 404 provides a user interface for receiving, from auser such as an administrator, the request for migration of a virtualmachine 406 b from one physical machine 100 to another. In furtherembodiments, the management component 404 a identifies a computingdevice 100 b on which to execute a requested virtual machine 406 d andinstructs the hypervisor 401 b on the identified computing device 100 bto execute the identified virtual machine; such a management componentmay be referred to as a pool management component.

Referring now to FIG. 4C, embodiments of a virtual application deliverycontroller or virtual appliance 450 are depicted. In brief overview, anyof the functionality and/or embodiments of the appliance 200 (e.g., anapplication delivery controller) described above in connection withFIGS. 2A and 2B may be deployed in any embodiment of the virtualizedenvironment described above in connection with FIGS. 4A and 4B. Insteadof the functionality of the application delivery controller beingdeployed in the form of an appliance 200, such functionality may bedeployed in a virtualized environment 400 on any computing device 100,such as a client 102, server 106 or appliance 200.

Referring now to FIG. 4C, a diagram of an embodiment of a virtualappliance 450 operating on a hypervisor 401 of a server 106 is depicted.As with the appliance 200 of FIGS. 2A and 2B, the virtual appliance 450may provide functionality for availability, performance, offload andsecurity. For availability, the virtual appliance may perform loadbalancing between layers 4 and 7 of the network and may also performintelligent service health monitoring. For performance increases vianetwork traffic acceleration, the virtual appliance may perform cachingand compression. To offload processing of any servers, the virtualappliance may perform connection multiplexing and pooling and/or SSLprocessing. For security, the virtual appliance may perform any of theapplication firewall functionality and SSL VPN function of appliance200.

Any of the modules of the appliance 200 as described in connection withFIG. 2A may be packaged, combined, designed or constructed in a form ofthe virtualized appliance delivery controller 450 deployable as one ormore software modules or components executable in a virtualizedenvironment 300 or non-virtualized environment on any server, such as anoff the shelf server. For example, the virtual appliance may be providedin the form of an installation package to install on a computing device.With reference to FIG. 2A, any of the cache manager 232, policy engine236, compression 238, encryption engine 234, packet engine 240, GUI 210,CLI 212, shell services 214 and health monitoring programs 216 may bedesigned and constructed as a software component or module to run on anyoperating system of a computing device and/or of a virtualizedenvironment 300. Instead of using the encryption processor 260,processor 262, memory 264 and network stack 267 of the appliance 200,the virtualized appliance 400 may use any of these resources as providedby the virtualized environment 400 or as otherwise available on theserver 106.

Still referring to FIG. 4C, and in brief overview, any one or morevServers 275A-275N may be in operation or executed in a virtualizedenvironment 400 of any type of computing device 100, such as any server106. Any of the modules or functionality of the appliance 200 describedin connection with FIG. 2B may be designed and constructed to operate ineither a virtualized or non-virtualized environment of a server. Any ofthe vServer 275, SSL VPN 280, Intranet UP 282, Switching 284, DNS 286,acceleration 288, App FW 280 and monitoring agent may be packaged,combined, designed or constructed in a form of application deliverycontroller 450 deployable as one or more software modules or componentsexecutable on a device and/or virtualized environment 400.

In some embodiments, a server may execute multiple virtual machines 406a-406 n in the virtualization environment with each virtual machinerunning the same or different embodiments of the virtual applicationdelivery controller 450. In some embodiments, the server may execute oneor more virtual appliances 450 on one or more virtual machines on a coreof a multi-core processing system. In some embodiments, the server mayexecute one or more virtual appliances 450 on one or more virtualmachines on each processor of a multiple processor device.

E. Systems and Methods for Providing A Multi-Core Architecture

In accordance with Moore's Law, the number of transistors that may beplaced on an integrated circuit may double approximately every twoyears. However, CPU speed increases may reach plateaus, for example CPUspeed has been around 3.5-4 GHz range since 2005. In some cases, CPUmanufacturers may not rely on CPU speed increases to gain additionalperformance. Some CPU manufacturers may add additional cores to theirprocessors to provide additional performance. Products, such as those ofsoftware and networking vendors, that rely on CPUs for performance gainsmay improve their performance by leveraging these multi-core CPUs. Thesoftware designed and constructed for a single CPU may be redesignedand/or rewritten to take advantage of a multi-threaded, parallelarchitecture or otherwise a multi-core architecture.

A multi-core architecture of the appliance 200, referred to as nCore ormulti-core technology, allows the appliance in some embodiments to breakthe single core performance barrier and to leverage the power ofmulti-core CPUs. In the previous architecture described in connectionwith FIG. 2A, a single network or packet engine is run. The multiplecores of the nCore technology and architecture allow multiple packetengines to run concurrently and/or in parallel. With a packet enginerunning on each core, the appliance architecture leverages theprocessing capacity of additional cores. In some embodiments, thisprovides up to a 7× increase in performance and scalability.

Illustrated in FIG. 5A are some embodiments of work, task, load ornetwork traffic distribution across one or more processor coresaccording to a type of parallelism or parallel computing scheme, such asfunctional parallelism, data parallelism or flow-based data parallelism.In brief overview, FIG. 5A illustrates embodiments of a multi-coresystem such as an appliance 200′ with n-cores, a total of cores numbers1 through N. In one embodiment, work, load or network traffic can bedistributed among a first core 505A, a second core 505B, a third core505C, a fourth core 505D, a fifth core 505E, a sixth core 505F, aseventh core 505G, and so on such that distribution is across all or twoor more of the n cores 505N (hereinafter referred to collectively ascores 505.) There may be multiple VIPs 275 each running on a respectivecore of the plurality of cores. There may be multiple packet engines 240each running on a respective core of the plurality of cores. Any of theapproaches used may lead to different, varying or similar work load orperformance level 515 across any of the cores. For a functionalparallelism approach, each core may run a different function of thefunctionalities provided by the packet engine, a VIP 275 or appliance200. In a data parallelism approach, data may be paralleled ordistributed across the cores based on the Network Interface Card (NIC)or VIP 275 receiving the data. In another data parallelism approach,processing may be distributed across the cores by distributing dataflows to each core.

In further detail to FIG. 5A, in some embodiments, load, work or networktraffic can be distributed among cores 505 according to functionalparallelism 500. Functional parallelism may be based on each coreperforming one or more respective functions. In some embodiments, afirst core may perform a first function while a second core performs asecond function. In functional parallelism approach, the functions to beperformed by the multi-core system are divided and distributed to eachcore according to functionality. In some embodiments, functionalparallelism may be referred to as task parallelism and may be achievedwhen each processor or core executes a different process or function onthe same or different data. The core or processor may execute the sameor different code. In some cases, different execution threads or codemay communicate with one another as they work. Communication may takeplace to pass data from one thread to the next as part of a workflow.

In some embodiments, distributing work across the cores 505 according tofunctional parallelism 500, can comprise distributing network trafficaccording to a particular function such as network input/outputmanagement (NW I/O) 510A, secure sockets layer (SSL) encryption anddecryption 510B and transmission control protocol (TCP) functions 510C.This may lead to a work, performance or computing load 515 based on avolume or level of functionality being used. In some embodiments,distributing work across the cores 505 according to data parallelism540, can comprise distributing an amount of work 515 based ondistributing data associated with a particular hardware or softwarecomponent. In some embodiments, distributing work across the cores 505according to flow-based data parallelism 520, can comprise distributingdata based on a context or flow such that the amount of work 515A-N oneach core may be similar, substantially equal or relatively evenlydistributed.

In the case of the functional parallelism approach, each core may beconfigured to run one or more functionalities of the plurality offunctionalities provided by the packet engine or VIP of the appliance.For example, core 1 may perform network I/O processing for the appliance200′ while core 2 performs TCP connection management for the appliance.Likewise, core 3 may perform SSL offloading while core 4 may performlayer 7 or application layer processing and traffic management. Each ofthe cores may perform the same function or different functions. Each ofthe cores may perform more than one function. Any of the cores may runany of the functionality or portions thereof identified and/or describedin conjunction with FIGS. 2A and 2B. In this the approach, the workacross the cores may be divided by function in either a coarse-grainedor fine-grained manner. In some cases, as illustrated in FIG. 5A,division by function may lead to different cores running at differentlevels of performance or load 515.

In the case of the functional parallelism approach, each core may beconfigured to run one or more functionalities of the plurality offunctionalities provided by the packet engine of the appliance. Forexample, core 1 may perform network I/O processing for the appliance200′ while core 2 performs TCP connection management for the appliance.Likewise, core 3 may perform SSL offloading while core 4 may performlayer 7 or application layer processing and traffic management. Each ofthe cores may perform the same function or different functions. Each ofthe cores may perform more than one function. Any of the cores may runany of the functionality or portions thereof identified and/or describedin conjunction with FIGS. 2A and 2B. In this the approach, the workacross the cores may be divided by function in either a coarse-grainedor fine-grained manner. In some cases, as illustrated in FIG. 5Adivision by function may lead to different cores running at differentlevels of load or performance.

The functionality or tasks may be distributed in any arrangement andscheme. For example, FIG. 5B illustrates a first core, Core 1 505A,processing applications and processes associated with network I/Ofunctionality 510A. Network traffic associated with network I/O, in someembodiments, can be associated with a particular port number. Thus,outgoing and incoming packets having a port destination associated withNW I/O 510A will be directed towards Core 1 505A which is dedicated tohandling all network traffic associated with the NW I/O port. Similarly,Core 2 505B is dedicated to handling functionality associated with SSLprocessing and Core 4 505D may be dedicated handling all TCP levelprocessing and functionality.

While FIG. 5A illustrates functions such as network I/O, SSL and TCP,other functions can be assigned to cores. These other functions caninclude any one or more of the functions or operations described herein.For example, any of the functions described in conjunction with FIGS. 2Aand 2B may be distributed across the cores on a functionality basis. Insome cases, a first VIP 275A may run on a first core while a second VIP275B with a different configuration may run on a second core. In someembodiments, each core 505 can handle a particular functionality suchthat each core 505 can handle the processing associated with thatparticular function. For example, Core 2 505B may handle SSL offloadingwhile Core 4 505D may handle application layer processing and trafficmanagement.

In other embodiments, work, load or network traffic may be distributedamong cores 505 according to any type and form of data parallelism 540.In some embodiments, data parallelism may be achieved in a multi-coresystem by each core performing the same task or functionally ondifferent pieces of distributed data. In some embodiments, a singleexecution thread or code controls operations on all pieces of data. Inother embodiments, different threads or instructions control theoperation, but may execute the same code. In some embodiments, dataparallelism is achieved from the perspective of a packet engine,vServers (VIPs) 275A-C, network interface cards (NIC) 542D-E and/or anyother networking hardware or software included on or associated with anappliance 200. For example, each core may run the same packet engine orVIP code or configuration but operate on different sets of distributeddata. Each networking hardware or software construct can receivedifferent, varying or substantially the same amount of data, and as aresult may have varying, different or relatively the same amount of load515.

In the case of a data parallelism approach, the work may be divided upand distributed based on VIPs, NICs and/or data flows of the VIPs orNICs. In one of these approaches, the work of the multi-core system maybe divided or distributed among the VIPs by having each VIP work on adistributed set of data. For example, each core may be configured to runone or more VIPs. Network traffic may be distributed to the core foreach VIP handling that traffic. In another of these approaches, the workof the appliance may be divided or distributed among the cores based onwhich NIC receives the network traffic. For example, network traffic ofa first NIC may be distributed to a first core while network traffic ofa second NIC may be distributed to a second core. In some cases, a coremay process data from multiple NICs.

While FIG. 5A illustrates a single vServer associated with a single core505, as is the case for VIP1 275A, VIP2 275B and VIP3 275C. In someembodiments, a single vServer can be associated with one or more cores505. In contrast, one or more vServers can be associated with a singlecore 505. Associating a vServer with a core 505 may include that core505 to process all functions associated with that particular vServer. Insome embodiments, each core executes a VIP having the same code andconfiguration. In other embodiments, each core executes a VIP having thesame code but different configuration. In some embodiments, each coreexecutes a VIP having different code and the same or differentconfiguration.

Like vServers, NICs can also be associated with particular cores 505. Inmany embodiments, NICs can be connected to one or more cores 505 suchthat when a NIC receives or transmits data packets, a particular core505 handles the processing involved with receiving and transmitting thedata packets. In one embodiment, a single NIC can be associated with asingle core 505, as is the case with NIC1 542D and NIC2 542E. In otherembodiments, one or more NICs can be associated with a single core 505.In other embodiments, a single NIC can be associated with one or morecores 505. In these embodiments, load could be distributed amongst theone or more cores 505 such that each core 505 processes a substantiallysimilar amount of load. A core 505 associated with a NIC may process allfunctions and/or data associated with that particular NIC.

While distributing work across cores based on data of VIPs or NICs mayhave a level of independency, in some embodiments, this may lead tounbalanced use of cores as illustrated by the varying loads 515 of FIG.5A.

In some embodiments, load, work or network traffic can be distributedamong cores 505 based on any type and form of data flow. In another ofthese approaches, the work may be divided or distributed among coresbased on data flows. For example, network traffic between a client and aserver traversing the appliance may be distributed to and processed byone core of the plurality of cores. In some cases, the core initiallyestablishing the session or connection may be the core for which networktraffic for that session or connection is distributed. In someembodiments, the data flow is based on any unit or portion of networktraffic, such as a transaction, a request/response communication ortraffic originating from an application on a client. In this manner andin some embodiments, data flows between clients and servers traversingthe appliance 200′ may be distributed in a more balanced manner than theother approaches.

In flow-based data parallelism 520, distribution of data is related toany type of flow of data, such as request/response pairings,transactions, sessions, connections or application communications. Forexample, network traffic between a client and a server traversing theappliance may be distributed to and processed by one core of theplurality of cores. In some cases, the core initially establishing thesession or connection may be the core for which network traffic for thatsession or connection is distributed. The distribution of data flow maybe such that each core 505 carries a substantially equal or relativelyevenly distributed amount of load, data or network traffic.

In some embodiments, the data flow is based on any unit or portion ofnetwork traffic, such as a transaction, a request/response communicationor traffic originating from an application on a client. In this mannerand in some embodiments, data flows between clients and serverstraversing the appliance 200′ may be distributed in a more balancedmanner than the other approached. In one embodiment, data flow can bedistributed based on a transaction or a series of transactions. Thistransaction, in some embodiments, can be between a client and a serverand can be characterized by an IP address or other packet identifier.For example, Core 1 505A can be dedicated to transactions between aparticular client and a particular server, therefore the load 515A onCore 1 505A may be comprised of the network traffic associated with thetransactions between the particular client and server. Allocating thenetwork traffic to Core 1 505A can be accomplished by routing all datapackets originating from either the particular client or server to Core1 505A.

While work or load can be distributed to the cores based in part ontransactions, in other embodiments load or work can be allocated on aper packet basis. In these embodiments, the appliance 200 can interceptdata packets and allocate them to a core 505 having the least amount ofload. For example, the appliance 200 could allocate a first incomingdata packet to Core 1 505A because the load 515A on Core 1 is less thanthe load 515B-N on the rest of the cores 505B-N. Once the first datapacket is allocated to Core 1 505A, the amount of load 515A on Core 1505A is increased proportional to the amount of processing resourcesneeded to process the first data packet. When the appliance 200intercepts a second data packet, the appliance 200 will allocate theload to Core 4 505D because Core 4 505D has the second least amount ofload. Allocating data packets to the core with the least amount of loadcan, in some embodiments, ensure that the load 515A-N distributed toeach core 505 remains substantially equal.

In other embodiments, load can be allocated on a per unit basis where asection of network traffic is allocated to a particular core 505. Theabove-mentioned example illustrates load balancing on a per/packetbasis. In other embodiments, load can be allocated based on a number ofpackets such that every 10, 100 or 1000 packets are allocated to thecore 505 having the least amount of load. The number of packetsallocated to a core 505 can be a number determined by an application,user or administrator and can be any number greater than zero. In stillother embodiments, load can be allocated based on a time metric suchthat packets are distributed to a particular core 505 for apredetermined amount of time. In these embodiments, packets can bedistributed to a particular core 505 for five milliseconds or for anyperiod of time determined by a user, program, system, administrator orotherwise. After the predetermined time period elapses, data packets aretransmitted to a different core 505 for the predetermined period oftime.

Flow-based data parallelism methods for distributing work, load ornetwork traffic among the one or more cores 505 can comprise anycombination of the above-mentioned embodiments. These methods can becarried out by any part of the appliance 200, by an application or setof executable instructions executing on one of the cores 505, such asthe packet engine, or by any application, program or agent executing ona computing device in communication with the appliance 200.

The functional and data parallelism computing schemes illustrated inFIG. 5A can be combined in any manner to generate a hybrid parallelismor distributed processing scheme that encompasses function parallelism500, data parallelism 540, flow-based data parallelism 520 or anyportions thereof. In some cases, the multi-core system may use any typeand form of load balancing schemes to distribute load among the one ormore cores 505. The load balancing scheme may be used in any combinationwith any of the functional and data parallelism schemes or combinationsthereof.

Illustrated in FIG. 5B is an embodiment of a multi-core system 545,which may be any type and form of one or more systems, appliances,devices or components. This system 545, in some embodiments, can beincluded within an appliance 200 having one or more processing cores505A-N. The system 545 can further include one or more packet engines(PE) or packet processing engines (PPE) 548A-N communicating with amemory bus 556. The memory bus may be used to communicate with the oneor more processing cores 505A-N. Also included within the system 545 canbe one or more network interface cards (NIC) 552 and a flow distributor550 which can further communicate with the one or more processing cores505A-N. The flow distributor 550 can comprise a Receive Side Scaler(RSS) or Receive Side Scaling (RSS) module 560.

Further referring to FIG. 5B, and in more detail, in one embodiment thepacket engine(s) 548A-N can comprise any portion of the appliance 200described herein, such as any portion of the appliance described inFIGS. 2A and 2B. The packet engine(s) 548A-N can, in some embodiments,comprise any of the following elements: the packet engine 240, a networkstack 267; a cache manager 232; a policy engine 236; a compressionengine 238; an encryption engine 234; a GUI 210; a CLI 212; shellservices 214; monitoring programs 216; and any other software orhardware element able to receive data packets from one of either thememory bus 556 or the one of more cores 505A-N. In some embodiments, thepacket engine(s) 548A-N can comprise one or more vServers 275A-N, or anyportion thereof. In other embodiments, the packet engine(s) 548A-N canprovide any combination of the following functionalities: SSL VPN 280;Intranet UP 282; switching 284; DNS 286; packet acceleration 288; App FW280; monitoring such as the monitoring provided by a monitoring agent197; functionalities associated with functioning as a TCP stack; loadbalancing; SSL offloading and processing; content switching; policyevaluation; caching; compression; encoding; decompression; decoding;application firewall functionalities; XML processing and acceleration;and SSL VPN connectivity.

The packet engine(s) 548A-N can, in some embodiments, be associated witha particular server, user, client or network. When a packet engine 548becomes associated with a particular entity, that packet engine 548 canprocess data packets associated with that entity. For example, should apacket engine 548 be associated with a first user, that packet engine548 will process and operate on packets generated by the first user, orpackets having a destination address associated with the first user.Similarly, the packet engine 548 may choose not to be associated with aparticular entity such that the packet engine 548 can process andotherwise operate on any data packets not generated by that entity ordestined for that entity.

In some instances, the packet engine(s) 548A-N can be configured tocarry out the any of the functional and/or data parallelism schemesillustrated in FIG. 5A. In these instances, the packet engine(s) 548A-Ncan distribute functions or data among the processing cores 505A-N sothat the distribution is according to the parallelism or distributionscheme. In some embodiments, a single packet engine(s) 548A-N carriesout a load balancing scheme, while in other embodiments one or morepacket engine(s) 548A-N carry out a load balancing scheme. Each core505A-N, in one embodiment, can be associated with a particular packetengine 548 such that load balancing can be carried out by the packetengine. Load balancing may in this embodiment, require that each packetengine 548A-N associated with a core 505 communicate with the otherpacket engines associated with cores so that the packet engines 548A-Ncan collectively determine where to distribute load. One embodiment ofthis process can include an arbiter that receives votes from each packetengine for load. The arbiter can distribute load to each packet engine548A-N based in part on the age of the engine's vote and in some cases apriority value associated with the current amount of load on an engine'sassociated core 505.

Any of the packet engines running on the cores may run in user mode,kernel or any combination thereof. In some embodiments, the packetengine operates as an application or program running is user orapplication space. In these embodiments, the packet engine may use anytype and form of interface to access any functionality provided by thekernel. In some embodiments, the packet engine operates in kernel modeor as part of the kernel. In some embodiments, a first portion of thepacket engine operates in user mode while a second portion of the packetengine operates in kernel mode. In some embodiments, a first packetengine on a first core executes in kernel mode while a second packetengine on a second core executes in user mode. In some embodiments, thepacket engine or any portions thereof operates on or in conjunction withthe NIC or any drivers thereof.

In some embodiments the memory bus 556 can be any type and form ofmemory or computer bus. While a single memory bus 556 is depicted inFIG. 5B, the system 545 can comprise any number of memory buses 556. Inone embodiment, each packet engine 548 can be associated with one ormore individual memory buses 556.

The NIC 552 can in some embodiments be any of the network interfacecards or mechanisms described herein. The NIC 552 can have any number ofports. The NIC can be designed and constructed to connect to any typeand form of network 104. While a single NIC 552 is illustrated, thesystem 545 can comprise any number of NICs 552. In some embodiments,each core 505A-N can be associated with one or more single NICs 552.Thus, each core 505 can be associated with a single NIC 552 dedicated toa particular core 505. The cores 505A-N can comprise any of theprocessors described herein. Further, the cores 505A-N can be configuredaccording to any of the core 505 configurations described herein. Stillfurther, the cores 505A-N can have any of the core 505 functionalitiesdescribed herein. While FIG. 5B illustrates seven cores 505A-G, anynumber of cores 505 can be included within the system 545. Inparticular, the system 545 can comprise “N” cores, where “N” is a wholenumber greater than zero.

A core may have or use memory that is allocated or assigned for use tothat core. The memory may be considered private or local memory of thatcore and only accessible by that core. A core may have or use memorythat is shared or assigned to multiple cores. The memory may beconsidered public or shared memory that is accessible by more than onecore. A core may use any combination of private and public memory. Withseparate address spaces for each core, some level of coordination iseliminated from the case of using the same address space. With aseparate address space, a core can perform work on information and datain the core's own address space without worrying about conflicts withother cores. Each packet engine may have a separate memory pool for TCPand/or SSL connections.

Further referring to FIG. 5B, any of the functionality and/orembodiments of the cores 505 described above in connection with FIG. 5Acan be deployed in any embodiment of the virtualized environmentdescribed above in connection with FIGS. 4A and 4B. Instead of thefunctionality of the cores 505 being deployed in the form of a physicalprocessor 505, such functionality may be deployed in a virtualizedenvironment 400 on any computing device 100, such as a client 102,server 106 or appliance 200. In other embodiments, instead of thefunctionality of the cores 505 being deployed in the form of anappliance or a single device, the functionality may be deployed acrossmultiple devices in any arrangement. For example, one device maycomprise two or more cores and another device may comprise two or morecores. For example, a multi-core system may include a cluster ofcomputing devices, a server farm or network of computing devices. Insome embodiments, instead of the functionality of the cores 505 beingdeployed in the form of cores, the functionality may be deployed on aplurality of processors, such as a plurality of single core processors.

In one embodiment, the cores 505 may be any type and form of processor.In some embodiments, a core can function substantially similar to anyprocessor or central processing unit described herein. In someembodiment, the cores 505 may comprise any portion of any processordescribed herein. While FIG. 5A illustrates seven cores, there can existany “N” number of cores within an appliance 200, where “N” is any wholenumber greater than one.

In some embodiments, the cores 505 can be installed within a commonappliance 200, while in other embodiments the cores 505 can be installedwithin one or more appliance(s) 200 communicatively connected to oneanother. The cores 505 can in some embodiments comprise graphicsprocessing software, while in other embodiments the cores 505 providegeneral processing capabilities. The cores 505 can be installedphysically near each other and/or can be communicatively connected toeach other. The cores may be connected by any type and form of bus orsubsystem physically and/or communicatively coupled to the cores fortransferring data between to, from and/or between the cores.

While each core 505 can comprise software for communicating with othercores, in some embodiments a core manager (not shown) can facilitatecommunication between each core 505. In some embodiments, the kernel mayprovide core management. The cores may interface or communicate witheach other using a variety of interface mechanisms. In some embodiments,core to core messaging may be used to communicate between cores, such asa first core sending a message or data to a second core via a bus orsubsystem connecting the cores. In some embodiments, cores maycommunicate via any type and form of shared memory interface. In oneembodiment, there may be one or more memory locations shared among allthe cores. In some embodiments, each core may have separate memorylocations shared with each other core. For example, a first core mayhave a first shared memory with a second core and a second share memorywith a third core. In some embodiments, cores may communicate via anytype of programming or API, such as function calls via the kernel. Insome embodiments, the operating system may recognize and supportmultiple core devices and provide interfaces and API for inter-corecommunications.

The flow distributor 550 can be any application, program, library,script, task, service, process or any type and form of executableinstructions executing on any type and form of hardware. In someembodiments, the flow distributor 550 may any design and construction ofcircuitry to perform any of the operations and functions describedherein. In some embodiments, the flow distributor distribute, forwards,routes, controls and/ors manage the distribution of data packets amongthe cores 505 and/or packet engine or VIPs running on the cores. Theflow distributor 550, in some embodiments, can be referred to as aninterface master. In one embodiment, the flow distributor 550 comprisesa set of executable instructions executing on a core or processor of theappliance 200. In another embodiment, the flow distributor 550 comprisesa set of executable instructions executing on a computing machine incommunication with the appliance 200. In some embodiments, the flowdistributor 550 comprises a set of executable instructions executing ona NIC, such as firmware. In still other embodiments, the flowdistributor 550 comprises any combination of software and hardware todistribute data packets among cores or processors. In one embodiment,the flow distributor 550 executes on at least one of the cores 505A-N,while in other embodiments a separate flow distributor 550 assigned toeach core 505A-N executes on an associated core 505A-N. The flowdistributor may use any type and form of statistical or probabilisticalgorithms or decision making to balance the flows across the cores. Thehardware of the appliance, such as a NIC, or the kernel may be designedand constructed to support sequential operations across the NICs and/orcores.

In embodiments where the system 545 comprises one or more flowdistributors 550, each flow distributor 550 can be associated with aprocessor 505 or a packet engine 548. The flow distributors 550 cancomprise an interface mechanism that allows each flow distributor 550 tocommunicate with the other flow distributors 550 executing within thesystem 545. In one instance, the one or more flow distributors 550 candetermine how to balance load by communicating with each other. Thisprocess can operate substantially similarly to the process describedabove for submitting votes to an arbiter which then determines whichflow distributor 550 should receive the load. In other embodiments, afirst flow distributor 550′ can identify the load on an associated coreand determine whether to forward a first data packet to the associatedcore based on any of the following criteria: the load on the associatedcore is above a predetermined threshold; the load on the associated coreis below a predetermined threshold; the load on the associated core isless than the load on the other cores; or any other metric that can beused to determine where to forward data packets based in part on theamount of load on a processor.

The flow distributor 550 can distribute network traffic among the cores505 according to a distribution, computing or load balancing scheme suchas those described herein. In one embodiment, the flow distributor candistribute network traffic according to any one of a functionalparallelism distribution scheme 550, a data parallelism loaddistribution scheme 540, a flow-based data parallelism distributionscheme 520, or any combination of these distribution scheme or any loadbalancing scheme for distributing load among multiple processors. Theflow distributor 550 can therefore act as a load distributor by takingin data packets and distributing them across the processors according toan operative load balancing or distribution scheme. In one embodiment,the flow distributor 550 can comprise one or more operations, functionsor logic to determine how to distribute packers, work or loadaccordingly. In still other embodiments, the flow distributor 550 cancomprise one or more sub operations, functions or logic that canidentify a source address and a destination address associated with adata packet, and distribute packets accordingly.

In some embodiments, the flow distributor 550 can comprise areceive-side scaling (RSS) network driver, module 560 or any type andform of executable instructions which distribute data packets among theone or more cores 505. The RSS module 560 can comprise any combinationof hardware and software, In some embodiments, the RSS module 560 worksin conjunction with the flow distributor 550 to distribute data packetsacross the cores 505A-N or among multiple processors in amulti-processor network. The RSS module 560 can execute within the NIC552 in some embodiments, and in other embodiments can execute on any oneof the cores 505.

In some embodiments, the RSS module 560 uses the MICROSOFTreceive-side-scaling (RSS) scheme. In one embodiment, RSS is a MicrosoftScalable Networking initiative technology that enables receiveprocessing to be balanced across multiple processors in the system whilemaintaining in-order delivery of the data. The RSS may use any type andform of hashing scheme to determine a core or processor for processing anetwork packet.

The RSS module 560 can apply any type and form hash function such as theToeplitz hash function. The hash function may be applied to the hashtype or any the sequence of values. The hash function may be a securehash of any security level or is otherwise cryptographically secure. Thehash function may use a hash key. The size of the key is dependent uponthe hash function. For the Toeplitz hash, the size may be 40 bytes forIPv6 and 16 bytes for IPv4.

The hash function may be designed and constructed based on any one ormore criteria or design goals. In some embodiments, a hash function maybe used that provides an even distribution of hash result for differenthash inputs and different hash types, including TCP/IPv4, TCP/IPv6,IPv4, and IPv6 headers. In some embodiments, a hash function may be usedthat provides a hash result that is evenly distributed when a smallnumber of buckets are present (for example, two or four). In someembodiments, hash function may be used that provides a hash result thatis randomly distributed when a large number of buckets were present (forexample, 64 buckets). In some embodiments, the hash function isdetermined based on a level of computational or resource usage. In someembodiments, the hash function is determined based on ease or difficultyof implementing the hash in hardware. In some embodiments, the hashfunction is determined based on the ease or difficulty of a maliciousremote host to send packets that would all hash to the same bucket.

The RSS may generate hashes from any type and form of input, such as asequence of values. This sequence of values can include any portion ofthe network packet, such as any header, field or payload of networkpacket, or portions thereof. In some embodiments, the input to the hashmay be referred to as a hash type and include any tuples of informationassociated with a network packet or data flow, such as any of thefollowing: a four tuple comprising at least two IP addresses and twoports; a four tuple comprising any four sets of values; a six tuple; atwo tuple; and/or any other sequence of numbers or values. The followingare example of hash types that may be used by RSS:

-   -   4-tuple of source TCP Port, source IP version 4 (IPv4) address,        destination TCP Port, and destination IPv4 address.    -   4-tuple of source TCP Port, source IP version 6 (IPv6) address,        destination TCP Port, and destination IPv6 address.    -   2-tuple of source IPv4 address, and destination IPv4 address.    -   2-tuple of source IPv6 address, and destination IPv6 address.    -   2-tuple of source IPv6 address, and destination IPv6 address,        including support for parsing IPv6 extension headers.

The hash result or any portion thereof may used to identify a core orentity, such as a packet engine or VIP, for distributing a networkpacket. In some embodiments, one or more hash bits or mask are appliedto the hash result. The hash bit or mask may be any number of bits orbytes. A NIC may support any number of bits, such as seven bits. Thenetwork stack may set the actual number of bits to be used duringinitialization. The number will be between 1 and 7, inclusive.

The hash result may be used to identify the core or entity via any typeand form of table, such as a bucket table or indirection table. In someembodiments, the number of hash-result bits are used to index into thetable. The range of the hash mask may effectively define the size of theindirection table. ny portion of the hash result or the hast resultitself may be used to index the indirection table. The values in thetable may identify any of the cores or processor, such as by a core orprocessor identifier. In some embodiments, all of the cores of themulti-core system are identified in the table. In other embodiments, aport of the cores of the multi-core system are identified in the table.The indirection table may comprise any number of buckets for example 2to 128 buckets that may be indexed by a hash mask. Each bucket maycomprise a range of index values that identify a core or processor. Insome embodiments, the flow controller and/or RSS module may rebalancethe network rebalance the network load by changing the indirectiontable.

In some embodiments, the multi-core system 575 does not include a RSSdriver or RSS module 560. In some of these embodiments, a softwaresteering module (not shown) or a software embodiment of the RSS modulewithin the system can operate in conjunction with or as part of the flowdistributor 550 to steer packets to cores 505 within the multi-coresystem 575.

The flow distributor 550, in some embodiments, executes within anymodule or program on the appliance 200, on any one of the cores 505 andon any one of the devices or components included within the multi-coresystem 575. In some embodiments, the flow distributor 550′ can executeon the first core 505A, while in other embodiments the flow distributor550″ can execute on the NIC 552. In still other embodiments, an instanceof the flow distributor 550′ can execute on each core 505 included inthe multi-core system 575. In this embodiment, each instance of the flowdistributor 550′ can communicate with other instances of the flowdistributor 550′ to forward packets back and forth across the cores 505.There exist situations where a response to a request packet may not beprocessed by the same core, i.e. the first core processes the requestwhile the second core processes the response. In these situations, theinstances of the flow distributor 550′ can intercept the packet andforward it to the desired or correct core 505, i.e. a flow distributorinstance 550′ can forward the response to the first core. Multipleinstances of the flow distributor 550′ can execute on any number ofcores 505 and any combination of cores 505.

The flow distributor may operate responsive to any one or more rules orpolicies. The rules may identify a core or packet processing engine toreceive a network packet, data or data flow. The rules may identify anytype and form of tuple information related to a network packet, such asa 4-tuple of source and destination IP address and source anddestination ports. Based on a received packet matching the tuplespecified by the rule, the flow distributor may forward the packet to acore or packet engine. In some embodiments, the packet is forwarded to acore via shared memory and/or core to core messaging.

Although FIG. 5B illustrates the flow distributor 550 as executingwithin the multi-core system 575, in some embodiments the flowdistributor 550 can execute on a computing device or appliance remotelylocated from the multi-core system 575. In such an embodiment, the flowdistributor 550 can communicate with the multi-core system 575 to takein data packets and distribute the packets across the one or more cores505. The flow distributor 550 can, in one embodiment, receive datapackets destined for the appliance 200, apply a distribution scheme tothe received data packets and distribute the data packets to the one ormore cores 505 of the multi-core system 575. In one embodiment, the flowdistributor 550 can be included in a router or other appliance such thatthe router can target particular cores 505 by altering meta dataassociated with each packet so that each packet is targeted towards asub-node of the multi-core system 575. In such an embodiment, CISCO'svn-tag mechanism can be used to alter or tag each packet with theappropriate meta data.

Illustrated in FIG. 5C is an embodiment of a multi-core system 575comprising one or more processing cores 505A-N. In brief overview, oneof the cores 505 can be designated as a control core 505A and can beused as a control plane 570 for the other cores 505. The other cores maybe secondary cores which operate in a data plane while the control coreprovides the control plane. The cores 505A-N may share a global cache580. While the control core provides a control plane, the other cores inthe multi-core system form or provide a data plane. These cores performdata processing functionality on network traffic while the controlprovides initialization, configuration and control of the multi-coresystem.

Further referring to FIG. 5C, and in more detail, the cores 505A-N aswell as the control core 505A can be any processor described herein.Furthermore, the cores 505A-N and the control core 505A can be anyprocessor able to function within the system 575 described in FIG. 5C.Still further, the cores 505A-N and the control core 505A can be anycore or group of cores described herein. The control core may be adifferent type of core or processor than the other cores. In someembodiments, the control may operate a different packet engine or have apacket engine configured differently than the packet engines of theother cores.

Any portion of the memory of each of the cores may be allocated to orused for a global cache that is shared by the cores. In brief overview,a predetermined percentage or predetermined amount of each of the memoryof each core may be used for the global cache. For example, 50% of eachmemory of each code may be dedicated or allocated to the shared globalcache. That is, in the illustrated embodiment, 2 GB of each coreexcluding the control plane core or core 1 may be used to form a 28 GBshared global cache. The configuration of the control plane such as viathe configuration services may determine the amount of memory used forthe shared global cache. In some embodiments, each core may provide adifferent amount of memory for use by the global cache. In otherembodiments, any one core may not provide any memory or use the globalcache. In some embodiments, any of the cores may also have a local cachein memory not allocated to the global shared memory. Each of the coresmay store any portion of network traffic to the global shared cache.Each of the cores may check the cache for any content to use in arequest or response. Any of the cores may obtain content from the globalshared cache to use in a data flow, request or response.

The global cache 580 can be any type and form of memory or storageelement, such as any memory or storage element described herein. In someembodiments, the cores 505 may have access to a predetermined amount ofmemory (i.e. 32 GB or any other memory amount commensurate with thesystem 575). The global cache 580 can be allocated from thatpredetermined amount of memory while the rest of the available memorycan be allocated among the cores 505. In other embodiments, each core505 can have a predetermined amount of memory. The global cache 580 cancomprise an amount of the memory allocated to each core 505. This memoryamount can be measured in bytes, or can be measured as a percentage ofthe memory allocated to each core 505. Thus, the global cache 580 cancomprise 1 GB of memory from the memory associated with each core 505,or can comprise 20 percent or one-half of the memory associated witheach core 505. In some embodiments, only a portion of the cores 505provide memory to the global cache 580, while in other embodiments theglobal cache 580 can comprise memory not allocated to the cores 505.

Each core 505 can use the global cache 580 to store network traffic orcache data. In some embodiments, the packet engines of the core use theglobal cache to cache and use data stored by the plurality of packetengines. For example, the cache manager of FIG. 2A and cachefunctionality of FIG. 2B may use the global cache to share data foracceleration. For example, each of the packet engines may storeresponses, such as HTML data, to the global cache. Any of the cachemanagers operating on a core may access the global cache to servercaches responses to client requests.

In some embodiments, the cores 505 can use the global cache 580 to storea port allocation table which can be used to determine data flow basedin part on ports. In other embodiments, the cores 505 can use the globalcache 580 to store an address lookup table or any other table or listthat can be used by the flow distributor to determine where to directincoming and outgoing data packets. The cores 505 can, in someembodiments read from and write to cache 580, while in other embodimentsthe cores 505 can only read from or write to cache 580. The cores mayuse the global cache to perform core to core communications.

The global cache 580 may be sectioned into individual memory sectionswhere each section can be dedicated to a particular core 505. In oneembodiment, the control core 505A can receive a greater amount ofavailable cache, while the other cores 505 can receiving varying amountsor access to the global cache 580.

In some embodiments, the system 575 can comprise a control core 505A.While FIG. 5C illustrates core 1 505A as the control core, the controlcore can be any core within the appliance 200 or multi-core system.Further, while only a single control core is depicted, the system 575can comprise one or more control cores each having a level of controlover the system. In some embodiments, one or more control cores can eachcontrol a particular aspect of the system 575. For example, one core cancontrol deciding which distribution scheme to use, while another corecan determine the size of the global cache 580.

The control plane of the multi-core system may be the designation andconfiguration of a core as the dedicated management core or as a mastercore. This control plane core may provide control, management andcoordination of operation and functionality the plurality of cores inthe multi-core system. This control plane core may provide control,management and coordination of allocation and use of memory of thesystem among the plurality of cores in the multi-core system, includinginitialization and configuration of the same. In some embodiments, thecontrol plane includes the flow distributor for controlling theassignment of data flows to cores and the distribution of networkpackets to cores based on data flows. In some embodiments, the controlplane core runs a packet engine and in other embodiments, the controlplane core is dedicated to management and control of the other cores ofthe system.

The control core 505A can exercise a level of control over the othercores 505 such as determining how much memory should be allocated toeach core 505 or determining which core 505 should be assigned to handlea particular function or hardware/software entity. The control core505A, in some embodiments, can exercise control over those cores 505within the control plan 570. Thus, there can exist processors outside ofthe control plane 570 which are not controlled by the control core 505A.Determining the boundaries of the control plane 570 can includemaintaining, by the control core 505A or agent executing within thesystem 575, a list of those cores 505 controlled by the control core505A. The control core 505A can control any of the following:initialization of a core; determining when a core is unavailable;re-distributing load to other cores 505 when one core fails; determiningwhich distribution scheme to implement; determining which core shouldreceive network traffic; determining how much cache should be allocatedto each core; determining whether to assign a particular function orelement to a particular core; determining whether to permit cores tocommunicate with one another; determining the size of the global cache580; and any other determination of a function, configuration oroperation of the cores within the system 575.

F. Systems and Methods for Maintaining Operation of a Multi-Core NetworkAppliance Upon Failover

Referring now to FIG. 6A, an embodiment of a system for controlling arate of a traffic traversing an intermediary 200 is illustrated. Inbrief overview, FIG. 6A depicts an intermediary 200 comprising a ratelimiting manager (RLM) 605 in communication with a rate limiting license660 which identifies a performance level 665. Data packets 601 arereceived by the RLM 605 and flow rate controlled by a throttler 625 ofthe RLM 605. Data packets 601 that are propagated or throttled by thethrottler 625 are sent out of the RLM 605 towards the packet engines548A-N which operate on the cores 505A-N. RLM 605 further includes atoken generator 610 for generating tokens 602 at a token rate 615 into atoken bucket 620 which holds or keeps a count of all the tokens 602. Anexcess handler 630 of the RLM 605 handles any data packets 601 that arenot received or not rate controlled by the throttler 625. RLM 605further includes a plurality of performance level settings 640A-640N.Each performance level setting (PLS) 640 may comprise a rate limitsettings 645 which may have a bucket settings 646 and a throughput rate650 comprising a bytes per second (BPS) limit 651 and a packet persecond (PPL) limit 652. As illustrated by FIG. 6A, RLM 605 may set,configure and manage a rate of flow of data packets 601 traversing thethrottle 625 at a rate limit that is identified by a performance level665 of the rate limiting license 660. The rate limit for propagatingdata packets 601 may be controlled by a number of tokens 602 which mayneed to be available for each propagated data packet 601.

Referring to FIG. 6A in a greater detail, rate limiting license 660 mayinclude any type and form of hardware, software or any combination ofhardware and software for providing a license, authorization or a permitto control a rate of network traffic received and/or transmitted via anappliance 200. In some embodiments, rate limiting license 660 includesany type and form of a program, an application, an executable, a script,a function, a unit or a device for providing a license or permit. Inother embodiments, rate limiting license 660 is a component of asoftware installed on the appliance 200. In further embodiments, ratelimiting license 660 includes a file, program, script or an executablethat is installed or enabled by an operator, administrator or a serviceprovider for the appliance 200. In some embodiments, rate limitinglicense 660 includes a third party software. Rate limiting license 660may include a license file validation. Intermediary 200 may use a filefor validating a license and use a link, a URL or a directory path tovalidate the rate limiting license 600. In some embodiments, a ratelimiting license 660 may be confirmed or verified via a remote databaseor link, such as for example MS Windows license verification model. Ratelimiting license 600 may include contents which upon testing orinspection by the intermediary may be validated as the rate limitinglicense 600. In some embodiments, rate limiting license 660 includes aunique identifier or a serial number for the appliance 200 or for anyservice provided by the appliance. In some embodiments, rate limitinglicense 660 may include a data structure, an object or an entry in adata base. The data structure, object or the entry may identify orprovide a license for an entity.

In further embodiments, rate limiting license 660 includes a component,unit, function or a program that controls a specific performance level.The specific performance level may correspond to a configuration oroperation of the appliance 200 in accordance with a predetermined set ofparameters or settings. In some embodiments, rate limiting license 660enables the appliance to be operate only at a single performance level.In other embodiments, rate limiting license 660 enables a plurality ofperformance levels for the appliance. In further embodiments, ratelimiting license 660 disables all except one performance level for theappliance 200. Rate limiting license 660 may include, provide oridentify one or more performance levels, such as the performance level665.

Performance level 665 may be any data or information for identifying orspecifying a level of performance of hardware, software or hardware andsoftware for an appliance 200, or any portion thereof. The level ofperformance may include a range or a limitation for a rate ofreceipt/transmit of network traffic or a rate of processing of datapackets, data or a data stream traversing an appliance 200. Performancelevel 665 may be identified via a file, an executable, a program, anapplication, a script, function, an algorithm, a unit or a device. Insome embodiments, performance level 665 includes anencryption/decryption key for decrypting and enabling a predeterminedperformance level to be used by the appliance 200. In other embodiments,performance level 665 includes a keyword or an instruction used by RLM605 to identify a predetermined set of performance level settings 645.In some embodiments, performance level 665 includes an algorithm,application, executable or unit that enables access to a set ofinstructions and settings that enable a level of performance of theappliance 200. Performance level 665 may comprise any number ofconfiguration settings and values, instructions, configuration files andexecutables, data values and any other type and form of hardware orsoftware to specify, identify and enable the appliance 200 to functionor operate at a level specified by the performance level 665.

Performance level 665 may include or specify any type and form ofinformation for identifying a level of performance or a level ofoperation of the appliance 200. In some embodiments, performance level665 includes an information about data flow rate threshold or alimitation for the receipt and/or transmit of data in bytes of data persecond or in data packets per second. The information about data flowrate may include a flow limit or an upper limit threshold for theperformance, or the data rate flow, for the appliance 200. In someembodiments, the information about data flow rate includes a lower limitthreshold for the performance, or the rate flow of data, of theappliance 200.

Rate limiting license 660 or the performance level 665 may identify orspecify any one performance level of a plurality of performance levelssupported by the appliance, such performance level 5500. Each of theperformance levels may identify a model or type of the appliance 200.Each of the performance levels may be associated with a predeterminedthreshold of performance or rate of performance or processing of thenetwork packets. For example, in some embodiments, performance level5500 limits the maximum rate of flow of the data packets traversing theappliance 200 at 5500 packets per second. In other embodiments,performance level 5500 limits the maximum rate of flow of the datapackets traversing the appliance 200 at 5500 bytes per second. Ratelimiting license 660 or the performance level 665 may identify orspecify performance level 7500. In some embodiments, performance level7500 limits the maximum rate of flow of the data packets traversing theappliance 200 at 7500 packets per second. In other embodiments,performance level 7500 limits the maximum rate of flow of the datapackets traversing the appliance 200 at 7500 bytes per second. Ratelimiting license 660 or the performance level 665 may identify orspecify performance level 9500. In some embodiments, performance level9500 limits the maximum rate of flow of the data packets traversing theappliance 200 at 9500 packets per second. In other embodiments,performance level 9500 limits the maximum rate of flow of the datapackets traversing the appliance 200 at 9500 bytes per second. Ratelimiting license 660 or the performance level 665 may identify orspecify performance level 10500. In some embodiments, performance level10500 limits the maximum rate of flow of the data packets traversing theappliance 200 at 10500 packets per second. In other embodiments,performance level 10500 limits the maximum rate of flow of the datapackets traversing the appliance 200 at 10500 bytes per second. Ratelimiting license 660 or the performance level 665 may identify orspecify performance level 12500. In some embodiments, performance levellimits the maximum rate of flow of the data packets traversing theappliance 200 at 12500 packets per second. In other embodiments,performance level 12500 limits the maximum rate of flow of the datapackets traversing the appliance 200 at 12500 bytes per second.

Data packets 601 may include any type and form of data and any type andform of units, groups or elements of data. Data packets 601 may includeany information, signal or transmission traversing an appliance 200.Data packets 601 may also include any type and form of formatted ornon-formatted data. In some embodiments, data packets 601 are formattedunits or chunks of data carried by a packet mode computer network. Theformatted units or chunks of data may be of a same size or a varyingsize. In further embodiments, data packets 601 are formatted or formednetwork data packets for a network 104. Data packets 601 may include aheader or an envelope. Data packets 601 may also include one or moredata bits or bytes. In some embodiments, data packets 601 are formed ororganized into groups that include 1, 2, 4, 8, 16, 24, 32, 48, 64, 96,128, 196 or 256 bits. Data packets 601 may include 1, 2, 4, 8, 16, 24,32, 48, 64, 96, 128, 196, 256, 512 or 1024 bytes. Data packets 601 mayalso include 1, 2, 4, 8, 16, 24, 32, 48, 64, 96, 128, 196, 256, 512 or1024 Megabytes.

Data packets 601 may be formed into a stream of data packets or a streamof data bits. Data packets 601 of a stream of data may be of a same or asimilar size. In some embodiments, data packets 601 of a stream of dataare of varying sizes. Data packets 601 may be formatted in any number ofways. Some data packets 601 may be formatted in accordance acommunication protocol, such as TCP, IP, UDP, HTTP, DHCP, POP3, SMPT,Citrix XenApp, Citrix ICA protocol or any other type and form ofcommunication protocol for any communication layer or level. In someembodiments, data packets 601 include compressed data packets. Some datapackets 601, in other embodiments, may be not compressed. In someembodiments, data packets 601 are formatted network packets, such asTCP/IP data packets. Data packets 601 may include any number of databits or bytes. In some embodiments, data packets 601 include a data bitor a data byte. In some embodiments, data packets 601 comprise one ormore data bits, or a stream of data bits. In further embodiments, datapackets 601 includes a byte. In further embodiments, data packets 601include a plurality of bytes. In some embodiments, data packets 601include a request from a client 102. In other embodiments, data packets601 include a response from a server 106. Data packets 601 may includeany number of formatted or non-formatted data groups, chunks or units ofdata. Data packets 601 may also include any number of bits, bytes,characters or any other units of information transmitted via a network104 or via an appliance 200.

Rate limiting manager 605, also known as RLM 605, may include any typeand form of algorithms or functions for managing or controlling a rateof operation, process or propagation of the network packets inaccordance with the performance level identified by the license. RLM 605may use instructions from the rate limiting license 660 to set up andconfigure the operation and function of the appliance 200 to processdata packets of the network traffic at a predetermined rate. By way ofexample, RLM 605 may use a token based system to control the rate atwhich data packets of the network traffic are received by one or morepacket engines 548. The token based system may include a token generatorthat generates tokens 602 at a token rate 615. The token based systemmay further include a token bucket 620 maintaining and keeping a trackof the tokens available and a throttler 625 which receives andpropagates data packets 601 conditioned by availability of tokens 602.As such the token based system controls the throughput of the datapackets 601 by throttling of the data packets 601 at a rate of availabletokens 602. The token based system may further include a performancelevel settings 640A-640N for each different performance level 665 thatthe license may identify. The performance level settings 640A-640N mayidentify various speeds or rates of processing of the data packets 601by the RLM 605. Each performance level settings 640 may further includerate limit settings 645 that includes a bucket settings 646 and athroughput rate 650. The throughput rate 650 may also include a bytesper second limit 651 and packets per second limit 652. RLM 605 mayidentify a performance level settings 645 for the appliance 200 inresponse to the performance level 665 of the rate limiting license andoperate in accordance with the identified settings. In some embodimentswhere the performance level 665 is not identified, RLM 605 may identifya default performance level settings 640 according to which theappliance 200 may operate. In some embodiments, the default performancelevel settings comprises the settings with the slowest rate ofoperation, propagation and throughput. RLM 605 may be operating on asingle-core system or a multi-core system. In a single core system, RLM605 may operate on the main central processing unit (CPU). In amulti-core system, RLM 605 may operate on a single or a plurality ofcores 505. RLM 605 may be configured to operate on each core 505 tocontrol the throughput rate for each packet engine 548 on each of thecores 505.

Rate limiting manager 605, also referred to as RLM 605, may include anyhardware, software or any combination of hardware and software forinitiating, establishing, managing, controlling and/or implementing ratelimiting of data traffic. RLM 605 may include any number of files,scripts, programs, applications, functions, algorithms, libraries,units, devices or executables for performing any function for limitingthe rate of any data traffic traversing the appliance 200. RLM 605 mayinclude any number of processors or processing units, logic circuits,analog or digital circuits for initiating, establishing, managing,controlling and implementing rate control of the data traffic. In someembodiments, rate limiting manager 605 comprises any functionality,logic, circuitry, software or applications for controlling the flow ofdata packets received by the appliance 200. Rate limiting manager 605may further include any number of RLM 605 components, such as any numberof the token generators 610, token rates 615, tokens 602, token buckets620, data packets 601, throttlers 625, excess handlers 630, performancelevels 640A-N, rate limit settings 645, bucket settings 646, throughputrates 650, BPS limits 651 and PPS limits 652. RLM may initiate andconfigure a set of RLM 605 components for each of the packet engines 548on each of the plurality of cores 505A-N. An appliance 200 may initiate,configure, set up and implement any number of RLMs 605 for any number ofPEs 548 which may run or operate on any number of cores 505A-N.

RLM 605 may include any functionality for controlling, managing,monitoring, accelerating or decelerating the flow or propagation of datapackets 601. In some embodiments, RLM 605 comprises controllers,functions or units that control, organize and manage a flow of datapackets 601. RLM 605 may include one or more queues for receiving orstoring incoming data packets 601. RLM 605 may further use or interfacewith any of the existing queues of the intermediary 200. The queuesaccessed, monitored, managed or used by the RLM 605 may correspond toany number of network interface cards (NICs) or data ports that receivedata packets 601 from one or more clients 102 or servers 106. Queuesused and managed by the RLM may include queues, such as a receivingqueue at the NICs or ports, SSL queues, queues storing compressednetwork traffic, queues storing decompressed network traffic, queuesstoring data specific applications, servers or clients, queues for theVIPs or virtual servers 270, queues for any component of theintermediary 200 or any network traffic for any component of theappliance 200. Similarly, RLM 605 may include one or more queues forreceiving and storing data packets 601 that are being received by thethrottler 625. In some embodiments, RLM 605 stores information or datapackets 601 from the queues intended for one or more packet engines 548on one or more cores 505. In some embodiments, RLM 605 includes anycomponent, unit or function for searching for and identifying ratelimiting license 660. RLM 605 may include functionality forcommunicating with the rate limiting license 660 and identifyingperformance level 665 information. RLM 605 may include functionality ormeans for recognizing and identifying the performance level 660. RLM 605may further include functionality or means for implementing rate limitsettings for the appliance 200 based on, or responsive to, theinformation identified by the performance level 660. RLM 605 may furtherinclude any functionality for generating operation and configurationsettings for the appliance 200 to implement the rate limit identified bythe performance level 665 of the rate limiting license 660.

Queues that are managed or accessed by the RLM 605 may be configured ina variety of ways. RLM 605 may manage, interface with or receive datapackets from any number of queues, such as the NICs queues or SSLqueues. The queues may configured to receive network traffic until theircapacity is reached. In some embodiments, queues receiving networktraffic are configured to drop, or tail drop, any additional networkpackets that cannot be accepted by the queue. In some embodiments, theNIC drops or tail drops packets. In further embodiments, if an amount ofnetwork packets received exceeds a predetermined threshold, the networkpackets may be dropped or not accepted by the queues. In furtherembodiments, when data packets are tail-dropped, data packets may beresent by the sender at a later time when queues are available to acceptadditional data packets.

A token 602 may include any value, character, number, count, object orany combination of hardware and software to be used for counting,maintaining or keeping a track of a number of data packets 601 that maybe propagated. A token 602 may include any file, object, character,symbol, value or a number to be used by any component of the RLM 605,such as a throttler 625 or a token bucket 620 for maintaining a count.The count maintained using tokens 602 may be any count, sum or tally fordetermining an amount or a number of data packets 602 to be propagated,processed or throttled by the RLM 605. Token 602 may include an object,an executable or a file. In further embodiments, token 602 includes acookie. In yet further embodiments, token 602 includes a set ofcharacters, values and parameters identifying a specific data packet601, or a specific type of data packet 601. Token 602 identifying aspecific data packet 601 or a specific data packet type may be used by athrottler 625 for propagating such a data packet 601. In someembodiments, one or more tokens 602 comprise a count or a summationvalue. In further embodiments, one or more tokens 602 are a value or anumber inside a counter or an algorithm maintaining a count or a totalfor the tokens 602. Tokens 602 may be counted or maintained by analgorithm or an application that keeps the count of tokens 602 by addingnew tokens 602 to the total count or subtracting existing tokens 602from the total count. Tokens 602 may be added or counted up in a counterat a token generation rate, such as token rate 615, for each new token602 generated. In some embodiments, tokens 602 are counted down orsubtracted from a total sum of tokens 602 for each data packet 601 thatis processed, propagated or throttled by the throttler 625. In furtherembodiments, token 602 comprises a number or a value that corresponds toa number of data packets 601 allowed for processing, propagating orthrottling at present moment. A token 602 may comprise any count, countvariable, value, number, object or component used for counting, keepingcount of or tracking a number of data packets 601 that may be allowed tobe propagated by the RLM 605.

Token generator 610 may include any hardware, software or anycombination of hardware and software for generating, managing, adding,subtracting, or otherwise controlling a count of tokens 602. Tokengenerator 610 may include any number of files, scripts, programs,applications, functions, algorithms, processing units, logic circuits,analog or digital circuits or executables for producing, managing,adding or subtracting tokens 602. Token generator 610 may comprise anyfunctionality and means for generating, maintaining and keeping a trackof a total count or a total number of tokens 602 available. Tokengenerator 610 may subtracts a token 602 or a count for each data packet601 that propagates, processes or throttles through the RLM 605. In suchembodiments, token generator 610 may add a token 602 or a count for eachperiod of time defined by a token rate 615 (1/(token rate) intokens/second) for which a data packet 601 is not propagated, processedor throttled through the RLM 605. Token generator 610 may also add atoken 602 or a count for each data packet 601 that propagates, processesor throttles through the RLM 605. In such embodiments, token generator610 subtracts a token 602 or a count for each period of time defined bya token rate 615 for which a data packet 601 is not propagated,processed or throttled through the RLM 605. Token generator 610 may addor generates any number of tokens 602 as defined by the token rate 615.In some embodiments, token generator 610 may subtract, count down orterminate any number of tokens 602 as defined by the token rate 615.Token generator 610 may include a program, an application or analgorithm counting, or maintaining a count. Token generator 610 maymaintain a number of counts or tokens 602 available at each moment. Insome embodiments, token generator 610 generates or adds a number oftokens to a total number of tokens 602. In some embodiments, tokengenerator 610 subtracts or terminates a number of tokens 602 from atotal number of tokens 602.

Adding, subtracting, generating or terminating or any other actionperformed by the token generator 610 on the tokens 602 may be responsiveto a timing counter defined by a token rate 615. In some embodiments,adding, subtracting, generating or terminating or any other actionperformed by the token generator 610 on the tokens 602 is responsive toa data packet 602 propagated, processed or throttled by the RLM 605.

Token rate 615 may be any rate at which tokens 602 are established,counted or generated. Token rate 615 may include any hardware, softwareor any combination of hardware and software for establishing orgenerating a rate, a tempo or a pace for production, counting orgenerating tokens 602. Token rate 615 may include an application, analgorithm, an executable or a counter for maintaining and managing arate at which tokens 602 are generated or terminated. In someembodiments, token rate 615 includes a rate for generating or increasinga number of tokens 602 in tokens 602 per second. In other embodiments,token rate 615 includes a rate of adding a count or counting up acounter that corresponds to a total number of tokens 602. In furtherembodiments, token rate 615 includes a rate for terminating ordecreasing a number of tokens 602 in tokens 602 per second. In otherembodiments, token rate 615 includes a rate of subtracting a count orcounting down a counter that corresponds to a total number of tokens602. In some embodiments, token rate 615 comprises any rate between 1and 100 bytes per second, such as 1, 10, 20, 30, 40, 50, 60, 70, 80, 90or 100 tokens 602 per second. In other embodiments, token rate 615includes any range of rates between 100 and 1000 tokens 602 per second,such as 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700,750, 800, 850, 900, 950 or 1000 tokens 602 per second. In furtherembodiments, token rate 615 includes any range of rates between 1000 and10000 tokens 602 per second, such as 1000, 1500, 2000, 2500, 3000, 3500,4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500or 10000 tokens 602 per second. In yet further embodiments, token rate615 includes any range of rates between 10,000 and 100000 tokens 602 persecond, such as 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000,50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000 or100000 tokens 602 per second. In still further embodiments, token rate615 includes any range of rates between 100,000 and 1,000,000 tokens 602per second, such as 100000, 150000, 200000, 250000, 300000, 350000,400000, 450000, 500000, 550000, 600000, 650000, 700000, 750000, 800000,850000, 900000, 950000 or 1000000 tokens 602 per second. In yet furtherembodiments, token rate 615 includes any range of rates between1,000,000 and 1,000,000,000 tokens 602 per second, such as 1,000,000,5,000,000, 10,000,000, 50,000,000, 100,000,000, 500,000,000 or1,000,000,000 tokens 602 per second. Token rate 615 may be used formanaging or controlling the rate of propagation, processing orthrottling of data packets 602 through the throttler 625. Token rate 615may be created by the token generator 610 responsive to any informationor settings from any of the rate limiting license 660 or any performancelevel settings 640.

Token bucket 620 may include any hardware, software or any combinationof hardware and software for managing and maintaining a total count or atotal tally of available tokens 602. Token bucket 620 may include anylogic, application, function or an algorithm for maintaining a totalnumber or tally of tokens 602. Token bucket 620 may include any logic,application, function or an algorithm for establishing a maximum sizefor the token bucket 620. Token bucket 620 may refuse to acceptadditional tokens 602 once a maximum size for the tokens has beenreached. In some embodiments, token bucket 620 establishes the maximumsize of the token bucket 620 responsive to information from a PLS 640 ora performance level 665. Token bucket 620 may include any functionality,logic, or means for disabling additional tokens 602 from being generatedor being added to the token bucket 620 once a threshold is exceeded. Infurther embodiments, token bucket 620 comprises a limit or a thresholdfor a minimal number of tokens 602 that may be generated. In suchembodiments, token bucket 620 includes any functionality, logic, ormeans for ensuring that no additional tokens 602 are subtracted orterminated after the threshold has been exceeded. Token bucket 620 mayinclude, keep a track of, or keep a count of any number of tokens 602that are available. In some embodiments, token bucket 620 subtracts atoken 602 for each data packet 601 that is processed, propagated orthrottled via a throttler 625. In other embodiments, token bucket 620adds a token 602 for each data packet 601 that is processed, propagatedor throttled via a throttler 625. Token bucket 620 may provide anynumber of tokens 602 to the throttler 625 in response to the requestfrom the throttler 625 to send the tokens 602. Token bucket 620 may alsorefuse to provide tokens 602 to the throttler 625 responsive to a rule,logic or threshold limit. Token bucket 620 may use any function, device,unit or an algorithm to maintain and monitor any token 602 or the totalnumber of available tokens 602.

Throttler 625 may include any hardware, software or any combination ofhardware and software for establishing, controlling and managing theflow of any data packets 601 that are propagating, processing orthrottling via RLM 605. Throttler 625 may include any number of files,programs, applications, functions, algorithms, components, processingunits or logic circuits for propagating, processing, throttling orcontrolling the flow of any data packets 601 according to a throughputrate 650. Throttler 625 may process, propagate, throttle any number ofdata packets 601 responsive to availability of tokens 602 in a tokenbucket 620. Data packets 601 to be throttled or processed by thethrottler 625 may be stored in one or more queues. The queues mayreceive incoming data packets 601 from one or more network interfacecards. Throttler 625 may receive incoming data packets 601 from one ormore queues and throttle, propagate or process the data packets 601 atthe rate limit. Throttler 625 may utilize logic, functions, algorithmsor units for determining or monitoring the total number or a total countof tokens 602 available in the token bucket 620. Throttler 625 maycomprise any functionality for propagating data packets 601 responsiveto availability of tokens 602 in the token bucket 620. In someembodiments, throttler 625 comprises functionality for propagating datapackets 601 based on BPS limit 651. In other embodiments, throttler 625comprises functionality for propagating data packets 601 based on PPSlimit 651. In further embodiments, throttler 625 comprises functionalityfor propagating or throttling data packets 601 based on any type andform of throughput rate 650 or token rate 615. Throttler 625 may includeany means or functionality for propagating or throttling data packet 601based on any combination of availability of tokens 602, throughput rate650, BPS limit 651, PPS limit 652 and any PLS 640A-N.

Throttler 625 may propagate, process or throttle any number of datapackets 601 responsive to availability of tokens 602. In someembodiments, throttler 625 determines to propagate a number of datapackets 601 to one or more packet engines 548 on one or more cores 505in response to a number of tokens 602 being available in the tokenbucket 620. In some embodiments, throttler 625 determines that aspecific number of data packets 601 is waiting at a queue to bepropagated to one or more packet engines 548. Throttler 625 may furtherdetermine that the total number of tokens 602 available in the tokenbucket 620 exceeds the number of data packets 601 awaiting thepropagation. Throttler 625 may propagate the data packets 601 responsiveto the tokens 602 being available for each data packet 601 propagated.In some embodiments, if the number of available tokens 602 does notexceed the number of data packets 601, throttler 625 may not propagatethe data packets. In further embodiments, once the data packets 601 arepropagated or throttled, the throttler 625 may send a signal to thetoken bucket 620 to decrease the number of available tokens 602 by thenumber of data packets 601 propagated. In further embodiments, throttler625 propagates the data packets 601 one at a time, while waiting toreceive a new token 602 from the token generator 610. Token rate 615 atwhich the token generator 610 generates tokens 602 may determine thethroughput rate 650 at which the throttler 625 propagates a data packet601. Following the propagation of each data packet 601, throttler 625may send an instruction to the token bucket to count down, decrease orotherwise adjust the number or tally of the available tokens 602. Inother embodiments, token rate 615 at which the token generator 610generates tokens 602 is determined by the throughput rate 650.

Throttler 625 may control the flow of the data packets 601 by using atoken 602 in correspondence to each byte or bit of data packets 601propagated by the throttler 625. In such embodiments, throttler 625controls the flow of the data packets 601 based on the number of bytesor bits of the data packets 601 propagated. For example, throttler 625may throttler or propagate data packets 601 towards one or more PEs 548,responsive to availability of tokens 602 for each byte or bit of datapackets 601 propagated. Following the propagation of the data packets601 based on the number of bits or bytes, the total number of tokens 602available in the token bucket 620 may decrease or adjust accordingly toreflect the correct total sum of available tokens 602. In someembodiments, throttler 625 may determine that a token bucket 620comprises no tokens 602. In such embodiments, throttler 625 readies adata packet 601 for propagation and awaits arrival of the next token602. Upon arrival of the token 602 the next token 602, throttler 625propagates the data packet 601. The token 602 may be dropped, discountedor subtracted from the count of the total number of available tokens 602responsive to the data packet 601 being propagated. Throttler 625 mayready another data packet 601 for transmission and await anotheravailable token 602 to implement the propagation. In some embodiments,throttler 625 decides that data packets 601 have been waiting forpropagation for a period of time that exceeds a predetermined threshold.Throttler 625 may then drop, flush or erase data packets 601 stored inthe queues awaiting the propagation. In some embodiments, throttler 625sends the data packets 601 whose waiting period has exceeded thethreshold to excess handler 630.

Excess handler 630 may include any hardware, software or any combinationof hardware and software for controlling and managing data packets 601sent to the excess handler from the throttler 625. Excess handler 630may include any number of files, programs, applications, functions,algorithms, components, processing units or logic circuits forpropagating, processing, terminating, refreshing or erasing any datapackets 601. Excess handler 630 may send, transmit out, reject or eraseany number of data packets 601 responsive to instructions from the PLS640. Excess handler 630 may terminate or flush data packets 601. In someembodiments, excess handler 630 sends the data packets 601 back to theoriginal sender of the data packets 601. In further embodiments, excesshandler 630 sends a response to the original sender of the data packets601 requesting from the sender to resend the data packets 601 again. Infurther embodiments, excess handler 630 stores the data packets 601received into a storage or a memory. In still further embodiments,excess handler 630 reformats or processes the data packets 601 and sendsthe data packets back to the queue of the throttler 625 for processing.In still further embodiments, excess handler 630 forwards the datapackets 601 to an additional throttler 625 that uses an additional setof tokens 602 from another token bucket 620. Following the receipt ofthe data packets 601 from the excess handler 630, the additionalthrottler 625 propagates or throttles the data packets to one or morePEs 548 responsive to availability of the additional set of tokens 602in the another token bucket 620.

Excess handler 630 may process any data packets 601 not throttled by thethrottler 625 in accordance with any number of processes and procedures.In some embodiments, excess handler 630 discards the data packets 601that are not received or processed by the throttler 625. For example,the queues storing data packets 601 may be flushed out if there are notokens 602 for processing the data packets 601. In further embodiments,excess handler 630 stores or maintains excess data packets 601 until thetokens 602 become available. In still further embodiments, excesshandler 630 maintains another token bucket for handling excess datapackets 601. Excess handler 630 may use active queue management tohandle any data packets 601 that are not processed, throttled orpropagated by the throttler 625. Excess handler 630 may include analgorithm or a function to use one or more proportional integrals tocalculate the number of data packets 601 to be flushed or handled in analternative matter, such as the additional token bucket. Excess handler630 may use probability functions or algorithms to calculate theprobability of the data packets 601 being dropped or flushed from thequeues. Active queue management may also employ current queue length,size of data packets, the number of data packets, token and throughputrates and BPS and PPS limits to compute the probability of data packets601 being dropped or flushed. In some embodiments, active queuemanagement may use current queue length, size of data packets, thenumber of data packets, token and throughput rates and BPS and PPSlimits to compute the probability to perform additional processes, suchas additional token bucket for processing the non-throttled data packets601. Active queue management may determine to proceed with processing ofthe data packets 601 for which the probability of being dropped exceedsa predetermined threshold.

Performance level settings 640, also referred to as PLS 640, may includeany hardware, software or any combination of hardware and software forsetting or configuring operation of the appliance 200. PLS 640 mayinclude any number of files, scripts, programs, applications, functions,algorithms, processing units, logic circuits, analog or digital circuitsor executables for configuring or setting operation or functionality ofany number of components of the appliance 200. PLS 640 may include anyfunctionality for configuring or setting the performance level oroperation of the appliance 200 in accordance with information identifiedby the performance level 665. In some embodiments, PLS 640 includes acompilation of configuration and operation settings for configuring ormaintaining the rate of flow of the data packets 601 traversing theappliance at a predetermined level. PLS 640 may comprise one or moresettings, parameters input values, instructions and commands for one ormore components of the intermediary 200 or the RLM 605. In someembodiments, PLS 640 includes parameters, inputs, instructions andsettings for any one of, or any combination of, the token generator 610,token rate 615, throttler 625, token bucket 620 and excess handler 630.The parameters, inputs, instructions and settings may include anycombination of values, configuration points and commands for any numberof components of the RLM 605 to maintain a rate of flow of data packets601 within a predetermined level or threshold.

PLS 640 may include any type and form of functionality for storing,identifying, setting and configuring any parameters, settings andinstructions for any part or component of the RLM 605. In someembodiments, PLS 640 includes settings, parameters and instructions fora token generator 610 to generate tokens 602 at a predetermined rate. Infurther embodiments, PLS 640 includes settings, parameters andinstructions identifying or specifying a token rate 615. PLS 640 mayinclude settings, parameters and instructions for specifying oridentifying a type of tokens 602 to be generated. In some embodiments,PLS 640 includes settings, parameters and instructions for generatingtokens 602 for data packets 601. In some embodiments, PLS 640 includessettings, parameters and instructions for generating tokens 602 for databytes or data bits of the data packets 601. PLS 640 may includesettings, parameters and instructions for initiating, generating andmaintaining a token bucket 620 which may include a maximum token size ofany number of tokens 602. In some embodiments, PLS 640 includessettings, parameters and instructions to establish and maintain a tokenbucket 620 that comprises any number of tokens 602, such as anywherebetween 100 and 1000, 1000 and 100000 or 100000 and 10,000,000 tokens.In some embodiments, PLS 640 includes settings, parameters andinstructions that generate a throttle 625. In further embodiments, PLS640 includes settings, parameters and instructions that set up, initiateand maintain the operation of throttle 625 to throttle or control rateor flow of data packets 601 at any rate or speed. In some embodiments,PLS 640 includes settings, parameters and instructions that initiate,establish, control and maintain an excess handler 630. In furtherembodiments, PLS 640 includes settings, parameters and instructions thatcontrol and maintain operation of excess handler 630 to handle, operateon or process any data packets 601 that are not processed or throttledby throttler 625.

PLS 640 may further include any additional settings, instructions orparameters for using additional methods for controlling of rate ofpropagation or processing. In some embodiments, PLS 640 includessettings and instructions for limiting amount of memory visible to thesystem, or the RLM 605. In further embodiments, PLS 640 includessettings and instructions for limiting a number of cores 505 availableto the system or the RLM 605. In still further embodiments, PLS 640includes settings and instructions for limiting the number of SSL chipsvisible to the system. In yet further embodiments, PLS 640 includessettings and instructions for adjusting a clock for running of theprocessors, such as CPUs or the processors used by the RLM 605. In stillfurther embodiments, PLS 640 includes settings and instructions formanaging processor cache-miss rate. In still further embodiments, PLS640 includes settings and instructions for tweaking or fine-tuning ofthe netio pipeline parameters. In yet further embodiments, PLS 640includes settings and instructions for running or operating RLM 605 on aplurality of cores 505. In still further embodiments, PLS 640 includessettings and instructions for running or operating RLM 605 on asingle-processor (single-core) system.

Rate limit settings 645 may include any hardware, software or anycombination of hardware and software for setting or configuring rate offlow of data packets 601. Rate limit settings 645 may include any numberof files, scripts, programs, applications, functions, algorithms,processing units, logic circuits, analog or digital circuits orexecutables for configuring or setting rate of flow or rate ofprocessing of data packets 601. Rate limit settings 645 may include anytype and form of settings, configuration points or setting points forany number of components of the RLM 605, such as the throttler 625, forcontrolling or limiting rate of flow or rate of propagation of datapackets 601. In some embodiments, rate limit settings 645 include anynumber of configuration and operation settings for establishing andoperating a token generator 610. In further embodiments, rate limitsettings 645 include any number of configuration and operation settingsfor establishing a token rate 615. In yet further embodiments, ratelimit settings 645 include any number of configuration and operationsettings for establishing and operating a throttler 625. In stillfurther embodiments, rate limit settings 645 include any number ofconfiguration and operation settings for establishing and operating anexcess handler 630. Rate limit settings 645 may include any numberfiles, instructions, data, applications, processing units, hardware orsoftware for configuring, establishing and operating any of the RLM 605components to maintain a rate of flow or propagation of the data 601through the throttler 625 within performance level settings identifiedby the performance level 665 of the rate limiting license 660. RLS 465may include any type and form of configuration or operationinstructions, parameters or settings. In some embodiments, RLS 465 setsthe limits or thresholds for any of the throughput rate 650 or tokenrate 615 based on the hardware platform of the model of the appliance200. In further embodiments, RLS 465 sets the limits or thresholds ofthe throughput and token rates at a minimum or the slowest rate settingsif a performance level 665 is not identified.

RLS 465 may configure a rate limit using a setting, such as:netscaler.do_rate_limit=1. In such embodiments, setting thenetscaler.do_rate_limit variable to non-zero activates or enables therate limiting settings. In other embodiments, if the setting is at azero, the rate limiting setting or code is not active. default value iszero, and means, that rate limiting code is not active.

RLS 465 may configure a size of a token bucket 620 using anothersetting, such as: netscaler.rate_limit_bucket_size=1000. In suchembodiments, the size of the token bucket 620 is set in milliseconds.This value may determine size of the maximum burst in traffic which willbe able to pass through throttler 625 without restrictions. This valuemay identify a maximum burst that is allowed to propagate or be receivedby the throttler 625.

RLS 465 may configure a limit for a throughput rate 650 using a settingsuch as: netscaler.rate_limit_mbits=3072. In such embodiments, the limitor the threshold for throughput rate is defined in Megabits per second,such as 3072 Mb/s, or 3 Gb/s.

RLS 465 may configure a packet rate limit in packets per second using asetting, such as: netscaler.rate_limit_packets=1000000. In suchembodiments, packet rate limit is defined as 1000000 packets per second.

RLS 465 may also allow confirmation of the values set. Suchconfirmations may be initiated using an instruction, such as: dmesg|grepplatform

RLS 465 may further configure or set rate limiting parameters, usinginstructions, such as: nsapimgr—B “w ns_rl_bucket_size 0x400”—forsetting a token bucket 620 size in milliseconds using hexadecimalvalues, nsapimgr—B “w ns_rl_mbits 0xC00”—for setting throughput rate inmegabits per second, using hexadecimal values, and nsapimgr—B “wns_rl_packets 0xF4240”—for setting a packet rate in packets per second,also using hexadecimal values.

Bucket settings 646 may include any hardware, software or anycombination of hardware and software for setting or configuring of tokenbucket 620. Bucket settings 646 may include any number of files,scripts, programs, applications, functions, algorithms, processingunits, logic circuits, analog or digital circuits or executables forconfiguring or setting any components features or functions of the tokenbucket 620. Bucket settings 646 may configure or set up a type oroperation of the token bucket 620. In some embodiments, bucket settings646 configure or set up the token bucket 620 as a bucket that stores apredetermined amount of tokens 602. Bucket settings 646 may configure orset up the token bucket 620 to enable a burst of data having a number ofdata packets 601 which does not exceed the number of tokens 602 storedin the token bucket 620 to be throttled or processed by the throttler625 without slowing the data 601 down. In further embodiments, bucketsettings 646 may maintain the rate of generating tokens 602 by the tokengenerator 610 at a predetermined token rate 615. In some embodiments,token rate 615 may be any rate of generating tokens 602, such as 10, 50,100, 500, 1000, 2000, 5000, 7000, 10000, 15000, 20000, 30000, 50000,100000 or 1000000 tokens/second. In some embodiments, bucket settings646 configure or set up the token bucket 620 as a bucket that does notstore a predetermined amount of tokens 602. Instead, token bucket 620may be set by the bucket settings 646 to simply hold a token 602 for apredetermined amount of time. The token bucket 620 may be configured todrop the token 602 after the predetermined amount of time expires andwait for the next token 602. Bucket settings 646 may configure or set upthe token bucket 620 not to enable a burst of data greater than apredetermined rate limit of data to be throttled. Instead, bucketsettings 646 may set up the token bucket to generate tokens 602 at apredetermined rate to ensure that data packets 601 are throttled orprocessed by the throttler 625 at the predetermined rate limit, such asthe throughput rate.

Throughput rate 650 may comprise any limit, threshold or a configurationsetting for a rate of processing or throttling of data packets 601traversing the appliance 200. Throughput rate 650 may include a rate orpropagation in packets per second or bytes per second of data packets601. Throughput rate 650 may include any hardware, software or anycombination of hardware and software for setting or configuring of tokenbucket 620. Throughput rate 650 may include any number of files,scripts, programs, applications, functions, algorithms, processingunits, logic circuits, analog or digital circuits or executables forconfiguring or setting rate of processing or throttling of data packets601. In some embodiments, throughput rate 650 includes a threshold for arate of propagation of data packets 601. In some embodiments, throughputrate 650 is identified in terms of data packets 601 to be processed,propagated or throttled per second. In other embodiments, throughputrate 650 is identified in terms of a number of packets or chunks of datapackets 601 to be processed, propagated or throttled per second. Infurther embodiments, throughput rate 650 is identified in terms of anumber of bits of data packets 601 to be propagated, processed orthrottled per second. In yet further embodiments, throughput rate 650 isidentified in terms of a number of requests of a client 102 to bepropagated, processed or throttled per second. In still furtherembodiments, throughput rate 650 is identified in terms of a number ofresponses of a server 106 to be propagated, processed or throttled persecond. In yet further embodiments, throughput rate 650 is identified interms of a number of transmissions for a specific destination to beprocessed, propagated or throttled per second. In still furtherembodiments, throughput rate 650 is identified in terms of a number oftransmission from a specific source to be processed, propagated orthrottled per second. In yet further embodiments, throughput rate 650 isidentified in terms of a number of data packets 601, data bits, databytes or transmissions to be throttled, processed or propagated andforwarded to a specific PE 548 or a specific core 505 of the appliance200. Throughput rate 650 may include any type and form of propagationrate for data packets 601 traversing the appliance 200.

Bytes per second limit 651, also referred to as BPS limit 651, maycomprise any limit, threshold or a configuration setting in bytes persecond for a rate of processing or throttling of data packets 601. BPSlimit 651 may include any rate of propagation in bytes per second. BPSlimit 651 may include any limit or threshold for a maximum rate ofpropagation in bytes per second. In some embodiments, BPS limit 651includes or identifies any rate between 1 byte per second and 1 terabyteper second. In some embodiments, BPS limit 651 includes any range ofrates between 1 and 100 bytes per second, such as 1, 10, 20, 30, 40, 50,60, 70, 80, 90 or 100 bytes per second. In other embodiments, BPS limit651 includes any range of rates between 100 and 1000 bytes per second,such as 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700,750, 800, 850, 900, 950 or 1000 bytes per second. In furtherembodiments, BPS limit 651 includes any range of rates between 1000 and10000 bytes per second, such as 1000, 1500, 2000, 2500, 3000, 3500,4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500or 10000 bytes per second. In yet further embodiments, BPS limit 651includes any range of rates between 10,000 and 100000 bytes per second,such as 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000, 50000,55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000 or 100000bytes per second. In still further embodiments, BPS limit 651 includesany range of rates between 100,000 and 1,000,000 bytes per second, suchas 100000, 150000, 200000, 250000, 300000, 350000, 400000, 450000,500000, 550000, 600000, 650000, 700000, 750000, 800000, 850000, 900000,950000 or 1000000 bytes per second. In yet further embodiments, BPSlimit 651 includes any range of rates between 1,000,000 and1,000,000,000 bytes per second, such as 1,000,000, 5,000,000,10,000,000, 50,000,000, 100,000,000, 500,000,000 or 1,000,000,000 bytesper second. Throughput rate 650 may include any hardware, software orany combination of hardware and software for setting or configuring oftoken bucket 620.

Packets per second limit 652, also referred to as PPS limit 652, maycomprise any limit, threshold or a configuration setting in packets persecond for a rate of processing or throttling of data packets 601. PPSlimit 652 may include any rate of propagation in packets per second. PPSlimit 652 may include any limit or threshold for a maximum rate ofpropagation in packets per second. In some embodiments, PPS limit 652includes or identifies any rate between 1 packet per second and1,000,000,000 packets per second. In some embodiments, PPS limit 652includes any range of rates between 1 and 100 packets per second, suchas 1, 10, 20, 30, 40, 50, 60, 70, 80, 90 or 100 packets per second. Inother embodiments, PPS limit 652 includes any range of rates between 100and 1000 packets per second, such as 100, 150, 200, 250, 300, 350, 400,450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950 or 1000 packetsper second. In further embodiments, PPS limit 652 includes any range ofrates between 1000 and 10000 packets per second, such as 1000, 1500,2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500,8000, 8500, 9000, 9500 or 10000 packets per second. In yet furtherembodiments, PPS limit 652 includes any range of rates between 10,000and 100000 packets per second, such as 10000, 15000, 20000, 25000,30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000,80000, 85000, 90000, 95000 or 100000 packets per second. In stillfurther embodiments, PPS limit 652 includes any range of rates between100,000 and 1,000,000 packets per second, such as 100000, 150000,200000, 250000, 300000, 350000, 400000, 450000, 500000, 550000, 600000,650000, 700000, 750000, 800000, 850000, 900000, 950000 or 1000000packets per second. In yet further embodiments, PPS limit 652 includesany range of rates between 1,000,000 and 1,000,000,000 packets persecond, such as 1,000,000, 5,000,000, 10,000,000, 50,000,000,100,000,000, 500,000,000 or 1,000,000,000 packets per second.

Referring now to FIG. 6B, embodiments of steps of a method forcontrolling a rate of traffic of a device in accordance with a ratelimit identified by a rate limiting license is illustrated. In briefoverview, at step 605 a rate limiting manager 605 of an intermediary 200identifies presence of a rate limiting license 660 that identifies aperformance level 665. At step 610, the rate limiting manager 605establishes a rate limit, such as a token rate 615, based on theperformance level 665. At step 615, a token generator 610 generatestokens 602 for a token bucket 620 in accordance with the rate limit. Atstep 620, the intermediary 200 receives a plurality of network packets,such as data packets 601. At step 625, a throttler 625 identifies, fromthe token bucket 620, tokens 602 for the plurality of network packets.At step 630, the throttler 630 controls a rate of receiving of thenetwork packets, such as the throughput rate 650, based on the ratelimit. At step 635, the rate limiting manager 605 transmits thethrottled network packets to one or more packet engines 548 andtransmits the network packets that were not throttled to an excesshandler 630. At step 640, the rate limiting manager 605 transmits thenetwork packets that were not throttled to an excess handler 630.

In further overview of FIG. 6B, at step 605 a rate limiting manager 605of an intermediary 200 identifies presence of a rate limiting license660 which includes an information about a performance of theintermediary 200. In some embodiments, a rate limiting manager (RLM) 605of the intermediary 200 identifies a presence of a rate limiting license660. In other embodiments, RLM 605 identifies a component of a ratelimiting license 660. In yet further embodiments, RLM 605 receives afile or a message from the rate limiting license 660 comprisinginformation about a performance of the intermediary 220. Rate limitinglicense 660 may sand to the RLM 605 any information about a performancelevel 665 for the appliance 200. The information about the performancelevel 665 may include any information about throughput rate 650 or apropagation or throttling rate of data packets 601. The informationidentifying the performance level 665 may include any number, value or aparameter uniquely identifying the performance level 665 from any otherperformance level 665. The performance level 665 may be matched by theRLM 605 with a corresponding performance level settings 640. Theperformance level 665 may include any information regarding the rate ofthroughput, propagation, throttling or processing of the data packets601 by the intermediary 200. In some embodiments, performance level 665includes a maximum threshold rate of throughput or propagation forprocessing or throttling data packets 601 via the throttler 625. Infurther embodiments, performance level 665 includes informationidentifying the rate of generating tokens 602. In still furtherembodiments, performance level 665 includes information identifying themaximum number of tokens 602 to be stored in a token bucket 620.

At step 610, the rate limiting manager 605 establishes a rate limitbased on the performance level 665. RLM 605 may establish a rate limitbased on the PLS 640 that is identified by the information from theperformance level 665. In some embodiments, PLS 640 generatesconfiguration and operation settings for the RLM based on theinformation from the performance level 665. RLM 605 may establish ordetermine a rate limit responsive to configuration and operationsettings from the PLS 640. RLM 605 may establishes any rate limiting orplacing a threshold for controlling throughput, propagation orthrottling of data packets 601. In some embodiments, RLM 605 establishesa throughput rate 650. In other embodiments, RLM 605 establishes a tokenrate 615. In further embodiments, RLM 605 establishes a BPS limit 651.In yet further embodiments, RLM 605 establishes a PPS limit 652. Infurther embodiments, RLM 605 establishes one or more bucket settings 646for a token bucket 620. In some embodiments, RLM 605 establishes amaximum token 602 number to be allowed by the token bucket 620. RLM 605may utilize PLS 640 to identify or establish any rates or rate limitsfor the RLM 605. In some embodiments, RLM 605 identifies or establishesa maximum or a minimum threshold or limit for a token rate 615. In otherembodiments, RLM 605 identifies or establishes a maximum or a minimumthreshold or limit for a throughput rate 615.

At step 615, a token generator 610 generates tokens 602 for a tokenbucket 620 in accordance with the rate limit. In some embodiments, tokengenerator 610 generates tokens 602 in accordance with, or based on, thethroughput rate 650. In other embodiments, token generator 610 generatestokens 602 in accordance with, or based on, the token rate 615. Infurther embodiments, token generator 610 generates tokens 602 inaccordance with, or based on, the BPS limit 651. In yet furtherembodiments, token generator 610 generates tokens 602 in accordancewith, or based on, PPS limit 652. In still further embodiments, tokengenerator 610 generates tokens 602 in accordance with, or based on, aPLS 640. In some embodiments, token generator 610 generates tokens 602in accordance with, or based on, information from the performance level665. In yet further embodiments, token generator 610 generates tokens602 in accordance with, or based on, the information about hardwareplatform for the appliance 200. In still further embodiments, tokengenerator 610 generates tokens 602 in accordance with, or based on,bucket settings 645, such as a token bucket 620 size limit. Tokengenerator 610 may generate tokens 602 responsive to a type of datapackets 601 traversing the appliance 200. Token generator 610 maygenerate tokens 602 responsive to any information from any of the RLM605 components, such as the PLS 640, token bucket 620, throttler 625 oran excess handler 630.

At step 620, the intermediary 200 receives a plurality of networkpackets, such as data packets 601. In some embodiments, the intermediary200 receives one or more requests from a client 102. In otherembodiments, the intermediary 200 receives one or more responses toclient 102 requests from a server 106. In further embodiments, theintermediary 200 receives one or more data bits or data bytes. In stillfurther embodiments, the intermediary 200 receives one or more streamsof data, such as stream data of audio or video streams. In someembodiments, the intermediary 200 receives one or more data packets 601.In further embodiments, the intermediary 200 receives a network datapacket, such as a data packet traversing the network 104. The receivedplurality of network data packets may be received by the intermediary200 and stored in one or more queues, registers or storages. Thereceived plurality of network data packets may be forwarded to thethrottler 625 for further processing, propagating or forwarding.

At step 625, a throttler 625 identifies, from a token bucket 620, tokens602 for the plurality of network packets. In some embodiments, throttler625 identifies a number of tokens 602 available in the token bucket 620.In other embodiments, throttler 625 identifies specific tokens 602 to beused for processing or propagating specific data packets 601. In furtherembodiments, throttler 625 identifies a current count or sum of thetokens 602 available. In further embodiments, throttler 625 requestsfrom the token bucket 620 a total sum of tokens 602 currently available.Token bucket 620 may respond to the throttler 625 with a responseidentifying the total sum or a total number of currently availabletokens 602. In some embodiments, throttler 625 identifies if there is atleast one token 602 available in the token bucket 620. In furtherembodiments, throttler 625 identifies if there is at least one token 602above a minimum threshold for the number of tokens available in thetoken bucket 620. Throttler 625 may identify each token 602 for eachdata packet 601 awaiting the propagation or processing. In someembodiments, throttler 625 identifies specific tokens 602 for specificdata packets 601 based on the type of tokens 602 and types of datapackets 601. Throttler 625 may assign one or more tokens 602 for one ormore network packets, such as data packets 601. In some embodiments,throttler 625 assigns one or more tokens 602 from the token bucket 620to a data packet 601. In other embodiments, throttler 625 assigns atoken 602 for one or more data packets 601. In further embodiments,throttler 625 assigns a token for each predetermined amount of bits,bytes or megabytes of the network packets or data packets 601. In stillfurther embodiments, throttler 625 assigns one or more tokens for eachbit, byte or megabyte of the network traffic or data packets 601.

At step 630, throttler 625 controls a rate of receiving, propagating orthrottling of network packets based on any rate limit. In someembodiments, throttler 625 controls a rate of receiving or propagatingof network packets, such as the data packets 601, based on theestablished rate limit. In some embodiments, throttler 625 controls arate of receiving, propagating or throttling of the data packets 601based on the throughput rate 650. In other embodiments, throttler 625controls a rate of receiving, propagating or throttling of the datapackets 601 based on the bytes per second (BPS) limit 651. In otherembodiments, throttler 625 controls a rate of receiving, propagating orthrottling of the data packets 601 based on the packet per second (PPS)limit 652. In further embodiments, throttler 625 controls a rate ofreceiving, propagating or throttling of the data packets 601 based onthe combination of BPS and PPS limits. In some embodiments, a throttler625 receives, throttles or propagates data packets 601 based on a ratethat does not exceed a predetermined packets per second limit 652 inaddition to not exceeding another predetermined bytes per second limit651. A throttle 625 may propagate, process or receive data packets 601based on any rate of bytes per second or packets per second providedthat the rate does not exceed a BPS or PPS limit. In some embodiments,throttle 625 propagates, processes or receives data packets 601 based onany rate of bytes per second that does not exceed a bytes per secondlimit 652. In still further embodiments, throttle 625 propagates,processes or receives data packets 601 based on a token rate 615. Thetoken rate 615 may further be based on any one of the BPS limit 651 orPPS limit 652. The token rate 615 may also be based on the combinationof BPS limit 651 and PPS limit 652. Throttler 625 may throttle,propagate or receive the network packets at any rate based on anycombination of any of the token bucket 620 maximum size, token rate 615,throughput rate 650, BPS limit 651 and PPS limit 652.

At step 635, the rate limiting manager 605 transmits data packets 601that were received, propagated or throttled by the throttler 625 to oneor more packet engines 548. In some embodiments, RLM 605 transmits thedata packets 601 from the throttler 625 to a PE 548. In otherembodiments, RLM 605 transmits some data packets 601 to a PE 548identified by the data packets 601. In further embodiments, RLM 605transmits subsets of data packets 601 to some specific or predeterminedPEs 548. The subsets of data packets 601 may include any number of datapackets. Such data packets may be distributed across any number of PEs548 operating on any number of cores 505. In further embodiments, RLM605 distributes the data packets 601 to the intended or packet engines548 based on the information from the data packets 601 or from theappliance 200.

At step 640, the rate limiting manager 605 transmits data packets 601that were not received, propagated or throttled by the throttler 625 toan excess handler 630. In some embodiments, RLM 605 determines that oneor more data packets 601 are pending at the throttler 625 for a periodof time that exceeds a predetermined threshold. RLM 605 may transmit orforward the one or more data packets to the excess handler 630 based onthe determination. In some embodiments throttler 623 determines thatsome data packets 601 need to be forwarded to the excess handler 630. Infurther embodiments, excess handler 630 monitors performance of thethrottler 625 and determines which data packets 601 need to be processedby the excess handler 630. In some embodiments, data packets 601 thatwere not received or propagated by the throttler 625 are sent to theexcess handler 630 for discarding or erasing. In further embodiments,data packets 601 that were not received or propagated by the throttler625 are sent to the excess handler 630 for further processing oranalyzing. In still further embodiments, data packets 601 that were notreceived or propagated by the throttler 625 are sent to the excesshandler 630 which notifies the sender of the data packets 601 that datapackets 601 are not received. Excess handler 630 may request the senderof the data packets 601 to resend the data packets that were received bythe handler 625.

1. A method for controlling a rate of a traffic of a device inaccordance with a rate limit identified by a rate limiting license, themethod comprising: a) identifying, by a rate limiting manager of anintermediary device, presence of a rate limiting license, theintermediary device processing network traffic between a plurality ofclients and a plurality of servers, the rate limiting licenseidentifying a performance level; b) establishing, by the rate limitingmanager, a rate limit based on the performance level of the ratelimiting license; and c) controlling, by a throttler of theintermediary, a rate of receiving network packets in accordance with therate limit.
 2. The method of claim 1, wherein step (a) further comprisesidentifying, by the rate limiting manager, the rate limiting license isnot present, and wherein step (b) comprises establishing a set of one ormore rate limit parameters for the rate limit for a lower performancelevel.
 3. The method of claim 1, wherein step (a) further comprisesidentifying, by the rate limiting manager, a type of hardware platformof the intermediary device, and wherein step (b) further comprisesestablishing the rate limit based on the type of hardware platform andthe performance level.
 4. The method of claim 1, wherein step (b)further comprises establishing, by the rate limiting manager, a maximumsize of a token bucket in milliseconds based on the rate limit for theperformance level of the rate limiting license.
 5. The method of claim4, wherein step (c) further comprises receiving, by the throttler, anetwork packet, determining that the token bucket has reached themaximum size and discarding the network packet in response to thedetermination.
 6. The method of claim 1, wherein step (b) furthercomprises establishing, by the rate limiting manager, a throughput ratelimit in bits per second based on the rate limit for the performancelevel of the rate limiting license.
 7. The method of claim 6, whereinstep (c) further comprises generating, by a token generator, a token fora token bucket at a rate specified by the throughput rate limit.
 8. Themethod of claim 1, wherein step (b) further comprises establishing, bythe rate limiting manager, a packet rate in packets per second based onthe rate limit for the performance level of the rate limiting license.9. The method of claim 8, wherein step (c) further comprises receiving,by the throttler, a network packet having a number of bytes, andremoving, by the throttler, a number of tokens from a token bucket equalto the number of bytes.
 10. The method of claim 8, wherein step (c)further comprises receiving, by the throttler, a network packet having anumber of bytes, determining, by the throttler, that a number of tokensin a token bucket is less than the number of bytes and not removing atoken from the token bucket.
 11. The method of claim 10, furthercomprises providing, by the throttler, the network packet to an excesspacket handler.
 12. A system for controlling a rate of a traffic of adevice in accordance with a rate limit identified by a rate limitinglicense, the system comprising: a rate limiting manager of anintermediary device identifying presence of a rate limiting license, theintermediary device processing network traffic between a plurality ofclients and a plurality of servers, the rate limiting licenseidentifying a performance level; the rate limiting manager establishinga rate limit based on the performance level of the rate limitinglicense; and a throttler of the intermediary controlling a rate ofreceiving network packets in accordance with the rate limit.
 13. Thesystem of claim 12, further comprising the rate limiting manageridentifying the rate limiting license is not present and establishing aset of one or more rate limit parameters for the rate limit for a lowerperformance level.
 14. The system of claim 12, further comprising therate limiting manager identifying a type of hardware platform of theintermediary device and establishing the rate limit based on the type ofhardware platform and the performance level.
 15. The system of claim 12,further comprising the rate limiting manager establishing a maximum sizeof a token bucket in milliseconds based on the rate limit for theperformance level of the rate limiting license.
 16. The system of claim15, further comprising the throttler receiving a network packet,determining that the token bucket has reached the maximum size anddiscarding the network packet in response to the determination.
 17. Thesystem of claim 12, further comprising the rate limiting managerestablishing a throughput rate limit in bits per second based on therate limit for the performance level of the rate limiting license. 18.The system of claim 17, further comprising a token generator generatinga token for a token bucket at a rate specified by the throughput ratelimit.
 19. The system of claim 12, further comprising the rate limitingmanager establishing a packet rate in packets per second based on therate limit for the performance level of the rate limiting license. 20.The system of claim 19, further comprising the throttler receiving anetwork packet having a number of bytes and removing a number of tokensfrom a token bucket equal to the number of bytes.
 21. The system ofclaim 19, further comprising the throttler receiving a network packethaving a number of bytes, determining that a number of tokens in a tokenbucket is less than the number of bytes and not removing a token fromthe token bucket.
 22. The system of claim 21, further comprising thethrottler providing the network packet to an excess packet handler.